I haven't gotten myself diagnosed but I have some sort of Anxiety Disorder. I freak out over stupid things. Like I had a best friend and it's natural to love your friends and think about them non romantically every once in a while right? Since I have a girlfriend I wasn't used to thinking about anyone other than her. Even if I only was thinking of my friend in a non romantic way. I froke out over that. Now I'm freaking out because I saw a Heterosexual Sex Scene (I'm a lesbian) it made me feel so uncomfortable. Now my stupid mind thinks I'm Bi? When I could never imagine myself with a guy. What should I do about my anxiety?
Recognise the thoughts are illogical. Sounds like it's the questioning aspect that's really causing you anxiety.
It is normal to think about anyone sexually or non sexually even when you're in a relationship.
Everyone feels uncomfortable watching sex that's outside their preference
I'm not a doctor but this sounds to me like you could have ocd. Google ocd intrusive thoughts, a lot of people haven't heard of this type of ocd before. The good news is I had it for a while but with medication and cbt my symptoms are pretty much under control.