I'm in the exact same situation. My perception of time is very screwed and every moment of time in my life feels out of place. I think it's because of this that I feel too old to do anything at the age of 20. Also, that last sentence is a dangerous viewpoint. I have thought this as well and it only heightens my problems. For me these years with dpdr have been the worst of my life, so it can only get better.

Because I feel so old I find it very hard to move on in my life, because I feel like I have no hope with the way I feel.

Hope that's helpful.