Why do I always get yelled at when my parents argue?

My parents kept arguing today about shit like the Christmas tree, cooking and other in my opinion dumb shit. I went downstairs to help my dad with the Christmas tree and see in the kitchen that I got a card so I ask my mom who sent it. Then she starts ranting about how she doesn't have the nerve for this, how I should stop bothering her and how she is always the one that gets asked stupid questions like this. This has been happening pretty much since I turned 15 and I'm so tired of it. Why am I the one that gets yelled at just because I'm there? I'm in my room or in a different one upstairs and they're mostly downstairs so why am I the one who gets yelled at? And then they complain that i don't want to hang out with them.

Dont even get me started on vacations or trips. One time we didn't go to a place my dad and I wanted to go because my mom got pissy. We also wanted to get ice cream. But guess what? Didn't do that either because of them. I'm sensitive as shit and yes I start crying when I get yelled at. My therapist thinks it might be because I might have autism which would explain a lot but my parents won't even let me get diagnosed because "stuff like that would never happen to our child."

I genuinely can't wait to move out. I'm tired of this and constantly getting yelled at or blamed just because my parents had a bad day. I get that they have their own problems and worries but letting that out on your child is shit.