I can’t help but have sexual thoughts about my crush

(This is a re-upload btw) Recently I’ve noticed I can’t get my crush out of my head. The only thing is that most times I think of him it’s sexual. My first time noticing this was when we were in class he went to talk to the teachers. I was sitting close to the teacher desk so I was looking around because i didn’t want to do my work. Than I started looking at him but while I was looking at him my eyes started to wonder down. And I saw his print he wasnt hard or anything but ofc you could see something he’s a guy. I just started thinking of how his dick would look mid class I only stopped. When my friend started talking to me. She joked saying I was so mesmerized by him and I was. But him and his cock💔. And it’s worse when I’m talking to him he has a pretty deep voice I get so nervous. And I end up thinking of how his voice would sound when moans. I was talking to him like last week at school. And I asked him what does he do when he’s at home. Out of honesty curiosity he’s the youngest and all his siblings moved out so he has the house to himself. He said “ I have a lot of free time so I’m in my room doing yk things if you get what I mean”. He was basically telling me he jerks off without it being too obvious. I said “get your freak on i guess”. And he smiled and than boom it’s been popping up in my head about him jerking off. If I see his hands i think about what he does with them I can’t stop thinking about him. If we’re walking and touching each other shoulders my mind wonders to different places. Hes much bigger than me so i think of what he would do to me. I feel like such a pervert and I feel even more like a pervert cus I’m a girl. I rarely ever heard girls think this way. And honestly if I was a guy I would be hard 24/7 by the thought of him. He’s just so cute even though he bigger than me he’s just so soft. And I feel so horrible when he’s talking about his interest. And I’m listening to him while thinking about his body naked. I Just want to know if these feeling and thoughts are normal. And if other people has had them before because I feel horrible having them.