(((Mandazzle)))
You sound similar to me and I think our answer is in your post..."Nobody knows how hard I am trying ... to make them not worry about me...to not fall apart...to not screw up".

I push people away because I don't want them to worry, I don't want to burden them with my issues, I try to be perfect and not show just how bad I feel so they believe everything is going well.

Yet I wonder why am I so lonely, why don't people want to be with me. Life is going on all around us yet we are not a part of it.

The answer, as much as we may not like it, is to reach out to people rather than wait for them to come to us. We have to learn to ask and accept help from others.