Can your sexuality change in your late 20s? just so feed up with this now just want to life my life

Ok so I’m a 17 year old female, and I’ve always thought I was straight. But I just really want to know how you would know the difference between so-ocd and actually questioning your sexuality. I have nothing against the LGBTQ community (in fact I am very much a token straight friend, lol) but I saw a video about comp-het recently and it sort of felt like what I was experiencing. I don’t want to be gay, I want to be with men, I want to like men, I’ve always liked men, but now I’m questioning whether or not that’s real? Because people can be gay but not want to be right? I’m single and I always have been. I think women are gorgeous, but when I try to imagine actually having any sort of romantic or sexual relationship with a woman it feels wrong, at least most of the time it does? Sometimes I’m less sure, and I’ve never been particularly boy crazy. I’ve liked maybe 2 or 3 people in my life, (not to say I’ve never found other guys attractive, but it doesn’t seem to be as often as most people) I have no particular reason to be afraid of being gay, very supportive family, safe area ect, but I don’t want to be, does that mean this is ocd, I don’t know what’s going on every time I say I’m straight I feel like I’m lying, but that might just be because I think about it so much. The idea of being with a woman doesn’t feel like something I would want, but is that just because I don’t want to want it? People online say things with so much sureness, if you feel like this it means this. Ect.

I feel so sad, alone, scared and hopeless. Until two months ago there was not even the remote possibility of being anything other than heterosexual and now the idea that I could find out that I was lesbian or bisexual terrifies me to death. Everything was born from the fact that I didn't feel sexual desire towards my ex-boyfriend and I started to be afraid that it was because I was a lesbian... how can I be a lesbian or bisexual if everything was born from this? I would like to run away from myself and my head. I would really like to go back and go back to my life before. I can't take it anymore. I just want to live my life like before

It feels like I’m lying to myself constantly and everyone. There feels like there is a weight on my heart from the moment I wake up till I go to sleep. I don’t want to be gay. Idk why it doesn’t register. Now everyone I see I have to see if I’m attracted to them. I see good looking men and I feel like I’m lying to myself that they are good looking, I see women and I see if im attracted to them. I look at everyone and I feel jealous. I want my fucking life back. But now my OCD (if this is even OCD) is telling me I was never happy and I was always suppressing my feelings of being gay. Why is this happening? Can OCD do this? I can’t enjoy anything ever.