Pls read, I can’t do this anymore

m 17 years old, female, im diagnosed with ocd , and ive been struggling a lot these past several years, but these past several weeks specifically have been hell, because it’s bringing back real events that took place when I was younger ,, when I was 5-7 I used to choke the pet kitties we had, I’m not sure why I would and i know I’d never do that again, just seeing other people yell at any animal makes me feel angry at the person and I can’t stand aggression towards animals, so I know I’ve changed and I was just a stupid kid. But what’s bothering me more is something else I did, I’m not sure if I’m remembering correctly, I was a terribly impulsive child, exposed to inappropriate/scary/pornographic content too young, I’m not sure what lead me to this but I was with my sister who is 5 years younger than me (1-3) at the time in my room, and I think I made our tongues touch… I don’t think I tried kissing or anything like that. Im not even totally sure if I’m remembering correctly either, But god, if I am, I can’t stop thinking about it, I feel sick everytime I do, I feel so much guilt, and I feel like I should tell my parents, why would I even do that?? It’s making me not wanna be around my sister, I feel like crying everytime I see her now, and my ocd makes me feel even worse than I already do about all of it, I know a while after that when I was a bit older maybe still under/around 10? Me and my older cousin did a challenge where we had to kiss to guess the flavor of a lip gloss,again not sure what lead to that.. I feel so gross specifically about the sister thing, the thing is I don’t actually remember doing it, I just remember licking my thumb afterwards and thinking to myself that it felt the same???? But I have no memory of how or what happened with the tongue thing. Idk. I just feel sick, I know I was a really bad child, I was mean and I was inappropriate at too young an age, and my father was always a bad example. I didn’t grow up with the best home life, but I don’t know if that’s an excuse. And me being only 17 now, I feel like I don’t deserve to live if I did something like that as a kid to my own sister. I love her very dearly and she’s one of my best friends, but idk if I can be near her anymore with all this in mind. Idk what to do. I feel horrible, any advice is appreciated.. sorry for talking so much