Sorry, I have no answers or insights as to what may be causing you to feel this way although it sounds like your self-esteem is a big factor.

If it's that low, maybe you're afraid to date because you might be afraid you'll let your guard down and someone will "see the act." Maybe you reject them out of fear that they ultimately will reject you. I really have no idea, just throwing some things out.

Have you talked to your T about these issues?

She/he will be able to help you get to the reasons why you react this way.

Good luck!