Mars is where you put your energy, Cancer is the sign of family/nurturing/caring, Saturn is the planet of responsibility and duty. Having Mars and Saturn in that sign indicates that at some time in your life, the necessity to care will become acute. What makes things "acute" is when Pluto comes along. Transiting Pluto (that's Pluto in its current position in the sky) is right on your Ascendant (Capricorn, also the sign of duties) and opposite your Mars. I notice the chart you posted was from 15th August, the current position of Pluto is 13.5 Capricorn (you can keep an eye on its position from the astro.com home page). Pluto brings experiences that drive us to the depths of our emotional range, they are often not pretty and not at all enjoyable. You'll feel some of your worst emotions (if you haven't already). It's a kind of purge. Old stuff will come up and be reviewed, especially anything you repressed from the past. It's a time when the psychological shadow in us (what we deny in ourselves, because we prefer not to look at it) will come up again and again.
If you note down the degrees of your Ascendant and Mars, and then look at the ephemeris for next year .....
http://www.astro.com/swisseph/ae/2000/ae_2016.pdf
.....you'll see that Pluto has moved away from your Mars a little, until it retrogrades (goes backwards) and then it is right opposite your Mars again around September/October so things may become acute after a bit of a reprieve earlier in the year.
Basically, things will continue as they are for most of this year, because Pluto will be transiting on your Ascendant (right now) and then turning direct soon to move forward to oppose your Mars again. But early next year, it moves on to 17 Capricorn, and the intensity might ease off.
You have a need for your own space, with Moon in Aquarius and trine Uranus the planet of freedom. This is a contrast to your Mars/Saturn in Cancer, there is a collision of archetypal patterns. One is freedom, the other is dutiful care of family.
You'll see that Saturn is also connected to Moon, for dutiful caring.
Next year too, transiting Uranus will oppose your natal Uranus in the 10th house, and since the 10th house is related to 'Mum', then there might be a release of the caring duties at that time. Again, you can see on the ephemeris when the opposition to Uranus will be exact. The Uranus/Uranus opposition is often a time of life when all things change, and since Moon is also at nearly the same degree, that involves your Mum/family/home/caring, all those things being represented by the Moon.
What is the issue with the sister? Jupiter in the 3rd house of siblings suggests that things could be better? Jupiter is usually happiness, but it is also a planet of freedom. And Uranus is the ruler of your 3rd house. Sister is not pulling her weight, taking some of the responsibility off you? It's likely that you have a stronger Saturn than she has. It just happens (karma or fate?) that some members of a family will be set up with a strong Saturn, and others will not and that explains why A is doing the caring, and B is not, and is not actually 'meant to'. If you can accept this role, then you can get through the period when Pluto is making it hard for you. The only way out is
through, as the saying goes.