Yeah - I can relate to this. Same thing with high school down to the speech, and at a top uni right now. I'm not sure how to answer your question, I went to see a doctor and they said I had ADHD but the process is not very scientific and I feel that the condition is overdiagnosed. I am not taking medication.

I think part of the issue could be immaturity...unable to give up the instant pleasure of whatever and do boring work, when everyone else is. I have also noticed that I often interrupt people and zone out in conversations, etc.

In the end, everything is always fine but I know most days are wasted.

I've tried a few different things but it doesn't stick, I've always thought that when I enter a competitive situation with a clear incentive (like work after college) that I would be more focused and motivated. In the meantime, I've been recently trying to keep a calendar/schedule tasks, but have a hard time sticking to it.

Do you say that meditation worked for you while you were doing it? I don't see why you would stop. One thing I did was exercise 2x/day till getting injured, and I felt that helped with general mood and a bit with productivity too.