It's probably HOCD, because if you were really gay you wouldn't be upset by it... you'd just like looking at guys and such stuff..
At most, you might be bi-curious, especially if you haven't experienced anything real with anyone..
And even if you would really be bisexual (attracted to guys and girls) you could still choose to be in a relationship or even married with a female, most likely.. And you could see it better then, if you like being in a relationship with a girl, or if there are very important things missing that you could only get elsewhere.. Many people who consider themselves bi-curious or bisexual, are still in perfectly straight relationships.. It's important to be honest with yourself though..
Look up HOCD online, on other forums, some therapists who are OCD specialists have articles about it too..
I think it's better to stay away from any porn right now, it might just confuse you.. you don't need to fantasize about anyone either..
And even if you 'were' gay, by any odd chance... so what? Yes, it might make life more difficult, you could still remain 'in the closet' about it and not tell anyone? You could meet some colorful folks and decide if this would be for you or not...?
I was terribly scared God wanted me to be a nun when I was 12 or so, maybe even younger.. sometimes I still get thoughts like this
But I know I'd be a terrible nun lol..
I have seen nuns and talked to them and read about them, I don't feel drawn to their lifestyle at all.. There's always an element of conscious choice in these things.. You can choose a certain lifestyle..
