HOCD or Denial? HELP!

Alright so I'm a 17 year old female and I've been suffering from what I hope is HOCD for a little over 9 months now. It all started when I thought a girl in my history class was pretty. After thinking this I immediately started panicking and asking myself "Am I gay?". This scared me because up until that point I had never questioned my sexuality in fact I was a little boy crazy. I would always fantasize about kissing/having sex with guys and what my future husband would be like, you know that sort of thing. Anyway every time I would get these thoughts I would have to start "checking" myself to make sure I was straight. I had lots of compulsions but to spare you some time I'll just name a few: watching gay and straight porn to see which one I liked better, looking at random women in public and asking do I want to kiss/have sex with her?, reading posts about OCD and HOCD to reassure myself that I was straight, I would even look at my past/current friendships with girls to see if I felt anything towards them. However despite all that checking and proof that I was straight my mind just keeps telling me "You're gay, just come out". It's worth mentioning that I've never been in a relationship before or even had my first kiss yet (I know kinda lame) but the fact is every time I would think about it I always pictured myself with a guy. I had crushes on guys, I had girl crushes too but I always thought those were normal plus they were never romantic or sexual. It has also gotten really hard to tell the difference between what's real or what's fake. I've even started to become desensitized to the whole thing which scares me because it feels like I'm slowly turning gay (Is that normal?). Anyway thanks for reading this and if you have any advice that would be great thanks.
Also just one last question: What's the difference between have HOCD and being in denail? Would you know if you were in denial?

Denial would be if you full desire, thoughts, and everything would be focused on same sex. But because of some reason(s) you are deny all of that. Example: someone grows up in a strict religious environment that sees homosexuality as evil. the culture around them is also very homophobic. At a young age a person may realize they are gay but because they are so indoctrinated in their youth, they go into denial.

but they will not fantasize, as you do, about boys.

and again, as has been said many times here - you can catch OCD playing with your mind when all you do is define homosexuality. by SEX. IT IS MUCH MORE THAN SEX.

and has been said even more on this site - PLEASE STOP CHECKING. Checking will only make it worse. Stop watching porn. Stop checking out other girls. Stop that little voice in your head that starts to have a conversation about it. Whenever it start, do something else.

Great point and post by Otter. "You can catch OCD when all it does is relate homosexuality to sex". That's the problem here, it's that if you were truly of homosexual orientation their would be more to your feelings than just sex. It is a combination of emotions desires and attraction as is any orientation. A typical HOCD sufferers mind would tell him he wants to have sex with nearly every man he sees on the street, as with a homosexual their are more certain well defined desires and their minds are not constantly telling them their gay their gay their gay. Their is a big difference between what an HOCD sufferer experiences and what an actual homosexual experiences.