i never used to fantasize about men before. im 15 and straight. recently i fantasized about a man unconsiuly. now im worrying that i might be gay. please replyy i need help

I need too know that I'm not insane, really. I am 16 and for the past two weeks, this has been completely ruining my health and happiness. I only recently came out as a lesbian like 3 months ago after a lot of confusion about my attraction since I used to think I liked men. At first, I felt so sure that I liked women, but lately, I've been having these unwanted thoughts about the possibility of liking men. I never used to feel this way, but now, every time I look at a man, my brain obsessively fixates on it. It forces me to imagine kissing him, loving him, things I don’t want, and then tries to convince me that I do. It’s painful. The thought of this fills me with fear and anxiety, leading to panic attacks and breakdowns. I don’t want these thoughts. I hate them with every fiber of my being, but I’m terrified that one day I’ll act on them and somehow like it. I used to think I liked men, but back then, I was in a very unhealthy space in a time of escapism and something deeply parasocial. I’ve only ever liked the attention and validation a man could give me, but these experiences are somehow treated as further proof that I’m "bisexual." I’ve never been in a real relationship with anyone, which makes my brain constantly challenge me—telling me, “You don’t even know what love feels like.” It won’t shut up. It keeps obsessively trying to make me prove that I’m a lesbian, testing my reactions and questioning my certainty. Is this normal?

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 really dont know if it is ocd anymore I dont want certain sexual things with my bf anymore that i used to like When i envision it with a girl it is so easy to envision and it feels like i want that , that will give me the satisfaction This feeling is making me really question if i am still into men , desire men sexually Is this still ocd , i really dont know anymore , as it is a feeling it is too real