Where to draw the line between questioning/curiosity and denial?

Hmm... Well, firstly, remember that you've only been thinking about this for a month. I know what it's like, to want guidance right away; it'd be much easier to feel like you understand everything as soon as possible. Well... you may know this, but it'll take time to work this all out. Because while we can help, in the end it'll be up to you to decide where to draw that line.

That being said, here's my thoughts on your situation: If you can be in relationships with both genders, have you considered you might be bisexual? Ah, but you say only sex with guys sound appealing to you. Well, I've seen people who label themselves hetro-romantic but homosexual. Maybe you're bi-romatic and homosexual? There are endless possibilities when it comes to finding a label for yourself. Just remember that you're not limited to just two options when you define yourself.

Hope that helps a bit.

 

I don't think denial works. (Take it from someone who's been on that river for 55 years.)
So that leaves curiosity and questioning. I think that's the sort of problem that requires the scientific method: hypothesize, experiment, observe results over time, reach conclusion.

For what it's worth. I wish society had been open enough, and I had been brave enough, to use that method myself back in the 60's.

 

I've been in a similar situation to you. Back about when I was in grade seven I began to question my sexuality, because well, my friend told me she was bi and admitted to having a crush on me. I had no problem with it and even got close to going out with her - she'd even kissed me and I'd liked it. I told my mum that my friend was bi and my mom went crazy on me and said I shouldn't hang out with her anymore. I got scared and put all the feelings I'd begun to have away and denied it. I only realized to myself about two months ago that I was pansexual. By the sounds of it, you're curious right now, and might be bisexual. If I were you I'd start to begin to inquire if maybe you aren't straight. Just tell yourself out loud that you might not be straight and see what you think of the idea. It may sound silly, but you should do this. It might help you see if the idea appeals to you or if it just doesn't feel right. You are probably in the questing stage right now, been there, just make sure no one pushes you into a stage of denial. If you feel like you aren't, then you might not be, just don't try to push it under the rug. Life isn't worth doing that and denying yourself a possible happiness you haven't experienced.
Right now it just seems like you're questioning and that is totally fine. Just don't lose yourself on the way and if it turns out in the end you don't, then that is totally fine, and if you are, that is totally fine. Just get used to the idea and if it seems like it is you, then don't deny it and be happy with however your answer turns out.