I'm sorry no one replied to this and I see it was some months ago you posted. If you are still checking here then how are you doing?
I understand what you are saying I think. You write you don't feel you are sharing about yourself, that you are a supportive friend but that you don't experience that closeness with others. Is that right?
It is similar for me and I think you hit the nail when you talk about not sharing about yourself/what you really believe. I think it's hard to connect without doing this.
Maybe you can work on this a little at a time with someone you trust? Telling them a little bit more about yourself.
It's a work in progress I find - hugs to you.