Hi Ixaee.
I just looked at the chart again in the light of what you shared. Some things came to me after I logged off the other day too. I'll put it all in the post in as coherent a way as I can.
I didn't pay due attention to the Capricorn MC yesterday, which seems to reflect the 'strict' component of your parenting. The MC ruling Saturn is in Virgo in the 5th, suggesting a very organised and considered approach to nurturing your son's unique individuality. Your laying down of healthy boundaries while you are his world will help him to meet the wider world with integrity and realism in the future. Saturn being in the 5th house means that he will find a stronger sense of integrity through experiences of self-realisation, and so his sense of who he uniquely is will filter naturally into his public life. Of course where Saturn is in the chart there is a danger of fear getting in the way to some extent, and he is probably predisposed to be self-critical - to fear not being special enough. I'm certainly not trying to lecture on parenting here, but in setting boundaries you might want to avoid saying anything critical about him. For example, 'You are....' He needs Saturn to be strong yet on his side - to contain the strong Pluto, Neptune and Cancer energies without suppressing them. I might normally suggest that a parent of a child with this chart check in with themselves about the various motivations for the boundaries being set. With Saturn in Virgo, there is sometimes an environmental factor which involves organisation motivated to some extent by fear. As you say, you have lots of responsibility on your own, which you are clearly taking very seriously. I'm not knocking this at all. But it's possible that lack of self-confidence could influence your reliance on boundaries - that's just one possible way that his Saturn could manifest in his external environment.
But the main reason I wanted to put another post on this thread was to share some thoughts about the Sun Pluto opposition and the Moon Neptune conjunction. Neptune and Pluto are of course quite nihilistic energies from the viewpoint of individual consciousness. If it is our fate to act as channels for these energies then obviously we must, but its very important to develop a strong individual ego so that we don't become taken over by them.
Taking the Moon first, although the Sun is seen as the light of consciousness, I like a description of the Moon which I once came across as being 'an alternative centre of awareness.' With Moon Neptune the instinctive ability to fulfil the individual's emotional and bodily needs can become lost in a mist of Neptunian universality. Your saying something like, 'Self-sacrifice becomes automatic and effortless,' in your post suggests that you are a good hook for that Moon Neptune conjunction, but if you don't look after your own emotional and bodily needs, you might be modelling the self-immolating tendencies of the aspect. By looking after your own lunar needs, you teach him that he doesn't have to sacrifice the physical and emotional satisfaction of being in a body. There are lots of healthy ways to bring in Neptune - dance might be good at some stage, especially with Mars involved. I wouldn't be surprised if he isn't already showing some nifty moves!
Because Chiron can symbolise rage at unfairness, and Mars can react angrily to the emancipating effects of Neptune, I'd encourage any parent of the child with this chart to look for any such feelings. The healthy pursuit of an ideal of motherhood doesn't necessarily have to exclude feeling angry about certain features of the parenting situation. That Moon is also in Aquarius after all - if the father was around and being a supportive co-parent and even partner, what else might you be doing along side being a mother? Does the unfairness mirror any situations that you witnessed or bore as a child?
And Venus is of course often a significator for the mother, and in your case the Sun too to some extent, although some of his Sun will always be projected on the father as he will imagine him to be. The Pluto opposition in his chart could reflect lots of things, including any feelings being carried by you (consciously or unconsciously) about being penned in by the necessity of your situation - powerless to carve the destiny you wish to. With Sun in Venus in Cancer, he probably would have projected lots of solar stuff onto you as the mother anyway. But nonetheless he will still probably imagine his father to be warm and loving (Cancer Venus). And possibly the Pluto opposition will crystallise as a sense that life took his father away. This could influence the way his own solar light emerges into the world - he may be predisposed to feel that there are forces out there which threaten his capacity to pursue his destiny. These forces could be out in the world, or unresolved issues within. By becoming more conscious of any Pluto issues you have, like resentment, feeling powerless, depression, etc you can lessen the amount of Pluto energy in the home environment for him to pick up on. This is just speculative of course - I'm throwing things out in case they're relevant.
I haven't really touched on Mars, which you especially asked about. With Neptune in Aquarius he is part of a generation which idealises the life of the group and of human potential. Chiron also in Aquarius makes him sensitive to any display of brutality or unfairness which flies in the face of the humanitarian ideals. The Moon being part of the stellium suggests that his instinctive responses and manner of feeling safe are in tune with these values. But Mars opposes from Leo - the aggressive urge is coloured by the need to express his unique character and purpose, so there is of course tension here. It obviously falls to you to show how these opposing energies can be reconciled. I think he needs to see you be a bit Leo sometimes, especially with Sun opposite Pluto and Saturn in the 5th. And when he has tantrums, is probably important that he doesn't end up feeling too guilty about them, as this might cause him to bury his Mars to some extent. Mars is in the 5th too.
In fact the opposition could be seen as falling across the 5th/11th house axis with Moon and Neptune so close to the 11th cusp. This brings it into line with the signs involved too, and suggests that issues around his sense of identity and how he takes that identity into group participation could be important as he gets older. Again, it obviously falls to you to model this. Finding a group activity that you could do together that involves free self-expression could be a good thing maybe.
He'll probably be quite stubborn at times, with Sun and chart-ruling Venus opposite Pluto, and Mars in Leo, plus Moon and Ascendant also in fixed signs. I'd say he'll benefit from learning the virtue of yielding by experiencing it in safe circumstances in which he doesn't feel humiliated, but I'm sure you would instinctively know how to handle that kind of thing.
I haven't covered the whole chart, and of course can only guess and speculate about the factors I have mentioned. But feel free to ask anything else if you like.
Best wishes,