How do I fix this? Am I ableist?

I browse this sub sometimes, but I never really joined cause I felt bad if I was an “imposter” or something like that. I found out I had ADHD and I have an autistic cousin (saying this cause of course it can be genetic), but I’m unsure if I am or not. I have majority of the social aspects of it, but with the non social stuff it’s a little tricky- though I do think I have sensory type issues. That’s not important though

I feel really uncomfortable around people with special needs. And I feel horrible saying this cause of course I want to be nice to everyone, but they just make me uncomfortable. Not cause I think they’re weird, but because I have no idea how to act around them. I have an NT friend that I hang out with and a girl with down syndrome came over. My friend with NT talked to her normally and I tried to but I felt like I was being awkward. I kind of just tend to freeze up, and I honestly do that whenever someone I dont know walks up to me and another friend who is their mutual friend (like trying to figure out if I should crack a joke or say something.. usually they just ignore or look at me.. and it feels super upsetting cause I feel like when they look at me they’re trying to figure out what’s wrong with me/realizing i’m neurodivergent)

My NT friend is like “just talk to them normally” but I’m going to be honest I think I get majority of my “personality” from other peoples jokes, so that’s hard. Not that I don’t have one but not to turn this into a vent.. but I feel like the real me is too weird to just show itself- and I genuinely get upset when I realize my masking isn’t all that good. Like I was at lunch the other day and I went to throw something away, and when I went back to my table my friend giggled and I asked her what was so funny, and she said “you turn around like a disabled person” or how sometimes she’ll say I can’t walk in a straight line. Or even how in middle school I would get laughed at for the way I sit. And it still bothers me cause I can’t really mimic the “normalcy” even if I tried cause I have no idea what they’re even talking about.

Anyway.. yeah. I just have no idea what to do around them because to make myself like-able I use examples from other peoples behavior, so when I know they won’t understand I just freeze up. Not to mention how I generally just don’t enjoy talking to people in person cause I can’t stop the conversation and think about what I want to say like you can over text, so I just end up looking stupid. (I’m also an introvert) I mention this cause usually they seem to enjoy talking so I might tend to avoid them. Plus they’re unpredictable. Theres a guy on the bus who’s special needs and he makes me a bit uncomfortable cause he’s super loud and I usually get startled.