Hi. There are some potentially difficult aspects in this chart, depending largely on how they were compounded by your early environment. But every placement has its positive and negative side.
Your inhibitions around communication are largely to do with, not just Mercury in Scorpio, but the Moon Mercury Pluto conjunction in Scorpio. Using a quadrant house system, this would be in the 10th house, which is connected with one's experience of being parented, often by the mother. But in any case, the Moon is also a mother-significator. Its likely that the way in which your mother communicated with you, and/or the things which played on her mind that she kept secret from you, have had an effect on you. The Moon's need for emotional closeness and Mercury's need to exchange information are perhaps inhibited by a lack of trust, perhaps because your mother, feeling disempowered herself, made you feel disempowered too. You may need to work on taking your power back from her, because otherwise you will always feel like you are in that power dynamic to some extent when connecting with other people. You don't necessarily need to confront her - you can just resolve the issue internally, though your interactions with her may change as a result, and this may lead to a confrontation of one kind or another.
If these placements reflect a lack of trust due to the early loss of your mother, or another person close to you, then there may still be some unresolved issues from that which are inhibiting you.
But already you have probably tapped into some of the positive attributes of these placements through acting, and perhaps the themes of your art also involve the portrayal of Plutonian processes which you would not be so insightful about without this placement.
Although Neptune is in the first house, Uranus is much closer to the ascendant. This perhaps doesn't get expressed in the usual, rebellious way because of your inhibitions. Perhaps it is projected onto the environment and manifests as an expectation of disruption. This, plus Chiron right on the descendant, add to the possibility that you experienced the loss of someone close to you in early life, and that this has stayed with you. Loss doesn't have to be physical of course - there could be a sense that someone didn't give you the love you needed from them
Some kind of loss is also perhaps reflected in the Venus Saturn conjunction, and of course Neptune in the first house.
It might be worth you saying something about where your inhibition might have 'come from' so that further comments by myself and others are more relevant to your situation.
I don't think that the 12th house is necessarily as bad as people think.It can reflect deeply fulfilling experiences of at-one-ness with life. People tend to struggle with it because they resist what is required of such at-one-ness, which is to play a part in the healing of issues left floating around in collective consciousness - usually because society is culturally and politically set up to neglect that issue. A family is a culture in itself, with its own politics, and so our earliest experiences of 12th house energies are often that we pick up issues that have been left unresolved by our parents and recent ancestors. So the very close Venus Saturn conjunction may reflect an ongoing 'family curse' involving lack of self-worth, which it has fallen to you to try to redeem for the benefit of future generations. So there can be a sense that 12th house energies are not gratifying. This doesn't mean that they will be the cause of one's undoing - though if they are neglected, they can undermine one's conscious aims. It may also be necessary to be alone with them - because you are sensitive to Venus/Saturn issues that society has neglected, you may need to distance yourself from society in order to turn things around and then offer your insights back - perhaps through your art or acting.
It is certainly a very difficult placement for romance, as is the Scorpio stellium. It is probably important that you find a partner who understands and shares your sensitivities to some extent. And also important that she or he is someone who does not feel the need to cause you to suffer so as to avoid suffering from these sensitivities themselves. Some people are born rather 'care-free' with what we might call a naive and superficial outlook on life, and they have to work on bringing substance to their existence. You, on the other hand, have been born with a decidedly limited amount of this care-free take on things, but instead you have 'gravity' and power at your fingertips. You perhaps just need to have more faith in yourself so that you can capitalise on these strengths.
I think that your vacillating is not so much to do with your Sagittarius side, but more to do with Mars in Libra, Venus conjunct Saturn in the 12th house, and Neptune in the first house. A difficultly placed Moon can also lead to apprehension.
No matter which house system is used (apart from wholesign houses) there is very strong emphasis on the last quarter of the house cycle. This quarter symbolises experiences of being a vehicle for the expression of collective values, which can involve both: the enjoyment of being part of a society (achievement in the 10th, enjoyment of culture and friendship in the 11th, fusion with some larger life in the 12th); and also bringing needed change to society (contributing to the continued strengthening of the social structure in the 10th, introducing progressive ideas in the 11th, and healing the 'ghosts of the past' in the 12th). This house emphasis therefore suggests that your most significant experiences won't be those where you are defining yourself as a unique individual just for the sake of individuality, but rather those where you are acting as a channel for the expression of an evolving society. You can still find yourself along the way of course, and help others to find themselves too - this is an innate part of a healthy collective.
