Don't know what to do anymore

I've had dysthymia since I was 15 years old (officially diagnosed when I was 19, but looking back, it started when I was 15). I also have autism spectrum disorder (which the dysthymia is probably related to). I've been in therapy and had coaching on and off since my diagnoses, but I still struggle so much in life and it doesn't seem to get better. I mean, I've learned a lot and understand myself much better now, but I still have as many mood swings and times of feeling down as I had a years ago and I'm 24 years old now. I know mental illness doesn't get fixed overnight, but I just don't seem to make much progress. One of the main reasons (according to me and my last therapist) is that I cannot activate/motivate myself to do things. It is so hard for me to just start doing something, especially if it is something new. This is the main reason that I had to stop therapy and the main reason for struggling in college. I'm still in college, but I don't think I'm going to make it if I cannot change myself. I just don't know how to do it or what could possibly help me. I just feel like a lost cause. It's not that I'm a total screw-up or anything, I mean, I have a girlfriend, I have some friends, I have pretty good contact with my family, I have my own place which I can keep clean and neat, etc. I don't know, it all just doesn't make sense anymore and every day is a struggle and I just don't want to struggle anymore but I don't know how it could every get better.