"So here's the crux of the matter: how do I know how much impact these things are having on my daily life when I have no idea what its like not to have them?"

If you don't know how much impact they have on your daily life, then they are having too much. I think you sense that you could have "better" things to do than nudge dishes and fluff towels or even think of the placement of dishes and how fluffy the towels will be in their closed cabinets and closets?

I think, generally, whatever symptoms get most in the way determines the top-most diagnosis when you have several. Symptoms are not "you" so, ideally, the fewer the better. However, we all have ways to cope and some of those are "symptoms" but, if we don't mind and they don't get in our way, then they're okay.

I use to deliberately talk to myself (and answer :-) and it would entertain my coworkers. It was fine with me, helped me get "another" person in there to help me better see what I was struggling with (the other person being the "me" I was talking to and who was answering but having friends at work comment too just made it even more helpful).

I had a compulsive habit symptom that took up a large part of my day and was my primary reason for being in therapy. The therapy got rid of it and though I remember I couldn't imagine what I would do with all my time if I didn't have my symptom, I now don't have it but don't use my time much better (but I'm retired now). I have been able to go back to school and get another couple of degrees though and do other projects I enjoy which I wouldn't have ever been able to do with the symptom still in place.

A lot of it is what bugs YOU the most (not your doctors) and what you'd like to work on and/or get rid of. If it doesn't bother you that you have to know what time it is all the time but does bother you that you talk to yourself, work on seeing what you and your doctors can do about that symptom background first?