You don't say how old you are, although it sounds like you're in your late teens. Iliketrees has given you some very accurate information. If you take the ADOS diagnostic test, you could do one of four modules, which are based on your age, development and the estimated severity of your condition. For instance, I did module 4, which is for adults or adolescents with fluent speech. Modules 1, 2, and 3 are for younger people with less fluency.
There's no hiding the fact that it can be quite stressful, but clinicians are aware of this. It might help to make some notes beforehand about things you want to say, or to jog your memory.
Don't worry. You'll be fine. I think you'll find it a rather liberating experience.