Feeling genuinely sexually repressed

Why are things so real the first time they’re in my mind and then when I think about it later it’s easier for me to be like wtf?? I was watching a movie earlier and the young girl had developed more in the chest area than the last movie and I felt the desire to check her out so I did. Then later I let myself imagine her having sex and I liked it. But now looking back I’m like ew. The boys in the movie have also developed as the movie went on and I couldn’t help but think that in their real life they’ve probably woken up to boners and s*men and stuff. And looking back it’s just ugh. Idk if it’s sexual relevance but I genuinely let myself indulge in these thoughts and groinal responses and I remember thinking to myself I don’t want to be attracted to little kids and how do I stop myself (everyone has attractive qualities so in younger boys I see man like qualities). Idk I need help. I wouldn’t type this out if I truly believe I was messed up but I’m still scared

I can't look at 18+ videos, comics, etc. I am straight, but SO-OCD tries to make me think I am not And the thoughts turns to feelings, and makes me scared, uncomfortable, sad, because I know this is not me. And when I try to imagine myself being with the woman on adult videos, and comics, my OCD gives gronal response not at the girl, and it fills me with fear, and anxiety, I always loved, and was attracted to women but I can't and it caused me to be depressed, and I keep ruminating I keep trying to focus on her, but it's so bad that I avoid those all the time now. I am wondering has anyone gone through something like this, or currently is, and wondering how you have done to combat this!

Every single time me and my boyfriend do anything sexual, I feel really really guilty about it after. We’ve never had sex before but have done other things and I don’t feel guilty about it in the moment, but afterwards I feel guilty. I don’t necessarily regret doing it but I just feel horrible as a human. He does not push himself on me in anyway and I know it’s all a me thing. He is very cautious in making sure I’m comfortable and feel okay, but I don’t start feeling guilty until afterwards. I feel like this always relates back to my faith, which has recently fallen off. I feel like I can’t talk to anyone about this because I always get told the benefits of waiting for marriage. And honestly I do understand that, but I don’t know that I want to wait. I feel like people keep shoving “waiting for marriage” down my throat and it draws me so much further from Christianity and makes things so much harder to feel close to God again. I just feel so lonely in feeling these things and scared I’m going to hell if I keep doing stuff with my boyfriend, but I genuinely don’t know what I believe in anymore and it’s draining me that my values are changing. I know it’s probably healthy and natural for values to change as you grow up, but I feel like there’s a stereotype of Christianity I have to adhere to and it makes me so anxious and scared I’m going to hell if I don’t get everything perfect. My relationship with Christ isn’t something that I involve others in because of how personal it is to me. But I just feel shamed upon by every other Christian and it makes me scared for myself and sad for the way society is making it such a black and white view of this religion.