Okay I relate to this like a lot (both the 'am I aroace or just aro or just ace or what' and the 'i think I show some autistic traits but not all and sometimes people tell me I might be autistic but self diagnosing feels wrong and what if I'm not'), and this is how I personally think of it: first on sexuality, there's no need to label yourself, and even if you do, there's absolutely nothing wrong with changing that label once you've learned more about yourself. I usually refer to myself as 'like 70% aroace' and the percentage may depend on the day. I've never had a crush, and I don't think I've ever been sexually/romantically attracted to anyone? (How do i even know if I'm attracted to sb??). But if I ever fall in love then that's fine, then I'll just call myself a gray ace or something. Or maybe just say that I'm me, and it's okay to only know vaguely what I might like as long as I'm comfortable being myself.
I feel like the thing with autism is more complicated, at least for me, maybe because to me it feels like falsely calling yourself autistic is somehow more insensitive. Like you're belittling the struggles of people if you say 'oh I struggle with that too, so badly' when you actually don't. But then again, there's no way to know if the amount you might struggle or the way you live and think are equivalent to what other autistic people feel. It's this thought of 'am I autistic enough to call myself autistic' that I'm still trying to get rid of myself. So until I can maybe get a diagnosis, I tell myself 'it's okay to struggle with some things, everyone has something that's difficult for them. And it's also okay to make use of the same tools and methods that autistic people do if they help me with those struggles, even if I'm not autistic'. For example, I once saw someone describe a method they use to manage their ADHD when learning. I still use that method, even though I'm pretty sure I don't have adhd? But it helps, so why not use it. I've noticed that I have no sensory issues with touch, and only rarely with too much noise, but I can't stand the artificial smells of a soap shop or sth, so if they bother me especially much? I avoid them, and it doesn't matter if they bother me because I have autism or because I have a sensitive nose, they bother me so I have every right to leave that soap store once it gets too much.
And when I want to share some things about how I might be autistic or how I identify with some autistic traits, then I just add that information: that I'm not sure I'm autistic, but I still struggle with that one thing! I also struggle with that thing you described there!! As long as I don't say anything like 'well I'm pretty sure I'm autistic but I don't have those sorts of problems, so you shouldnt have them either' I feel like that is fine.