Clarify on your repertoire. In your other post you said that you are above grade 8, which is impressive, meaning that you should know on how to practice, or is it just now that you run into stress problems. How many pieces are you working on right now?
It seems to me that the way you lose track of time while practicing is very good.When I practice, I often get up thinking I have been playing for 15 minutes, only to find that I was playing for more like 45 minutes or an hour.This seems very good to me, suggesting I really am getting into my playing.