First, good luck with that.
Second, my little brother suffers from ADHD and unfortunately has to take concerta on a daily basis. The thing that helped him the most with 'getting stuck' on things or 'losing his head' is making a cruel minute to minute daily planner and get rid of unnecessary dilemmas.
So for example:
7:00 wake up
7:10 get out of the shower
7:30 clothes & hair
7:50 breakfast.
It sounds stupid, but most mornings he would just lose himself in something irrelevant and always be late.
When you have a BIG board in your room telling you what to do it takes 'thinking' out of the equation.
So maybe you don't need that for getting ready in the morning, but I (ADD) use it for work. Every morning I make a list of all the things I need to do and the time I should spend on it (incl breaks) and stick to it. Even schedule in 3x 30 min "empty" spaces, for if something takes too long, you will get back to it in those 30 min periods.
Also, dunno if it's relevant for you, with my brother we saw a few problematic things that took a lot of time, for example: deciding what to eat for breakfast could take up 45 min. So those things that we recognized as problematic, we added to the board. So, Monday - cornflakes, Tuesday - bread + cheese.
Recognize what your main problems are, and try to eliminate them. (or ask your girlfriend/parents, they will know)