Yes, starting the assessment process from the beginning again would have been frustrating! I was worried I was going to have to do the same, as I was still on the waiting list when I moved back to uni, but fortunately they were happy to still see me even though I had moved out of the area.
Personally, I have only just been diagnosed, so I don't yet know whether that will give me more access to support than I already have. I'm really fortunate that my uni are supportive and have been happy to give me support without a formal diagnosis, because they thought it was fairly certain I WOULD be diagnosed. The main things I've had at uni are permission to record lectures/classes, a study skills mentor, and exam access arrangements so I can sit exams in a small room either alone or with very few other people. As I wasn't diagnosed in school, I don't know what specific accommodations are available and how strict they are on needing a formal diagnosis, but if you haven't already, you might find it helpful to look in the school/college life sub-board. I don't know how US-dominated it is, but hopefully there are some Brits in there who can help!
You might also like to look up the book "Freaks, Geeks, and Asperger Syndrome" by Luke Jackson. You can find information about it here: https://en.wikipedia.org/wiki/Freaks,_G ... r_Syndrome. I found it really useful at your age, when I first read it.