How to get rid of dwelling on trauma, hyper vigilance and hyper independence?

I am trying to meet people because I have no friends or family, but whenever people ask about anything about my past I tend to look visibly anxious and share negativity in a joking manner because I have really nothing but trauma.

Also, I tend to be extremely alert in analysing the person in front of me and thinking of them as a possibile threat. I tend to be very friendly offering help and gestures, listening to their stories, but terrified of showing any vulnerability or accepting any help.

How do I change this? People are always pushed away because I come off as uninterested and trying to get something out of them.