Hello Siftnsand.
Have you ever heard of Elaine Aron (and other psychologists) theories on the "Highly Sensitive Person"? Being introverted, imaginative and emotionally sensitive aren't necessarily bad things. I identify as an HSP myself, and I accept and enjoy those traits.
However, it seems that HSPs (like any other personality type) accumulate emotional baggage from specific negative life events they don't cope with well. I became socially anxious, defensive and also very "needy" at the time, after a period of school bullying and social rejection, for example. I remember being more socially confident and slightly more extraverted before these events. I swear this kind of experience leaves a mark - "schemas" - that doesn't go away without the kind of "debriefing" that therapy provides.
We ALL have insecurities, negative associations and self-defeating behaviors by the time we are adults. These lead to depressed moods and anxiety both directly and indirectly. The art of life is really to lead with and develop one's strengths, and overcome one's weaknesses where necessary. You seem to be doing that. Reading your posts here is helping me realize a few things about myself too.
I'm glad to hear you have tried therapy. Personally I don't tolerate meds very well, so therapy has become my preferred tool of choice, along with almost daily journaling and a lot of psychology books!