Slightly confused

I'm a 20 year old college student and I considered myself straight up until now. A few months back I was making out with this girl and something suddenly felt "wrong". I've kissed and made out with girls before and never got that feeling of "wrong" (might be because i was under the influence of alcohol). To add to this, this girl was out of my league but I didn't get any butterflies or my heart was beating fast or anything while we kissed like how I always imagined.Prior to this incident (maybe 2 months before) I noticed very weak erection to porn (I was a heavy porn user) and noticed that I started paying attention to the penis in porn which from my memory has never happened before. My focus was always the girl in porn and picturing me as the guy. I've had a girl crushes before where I would get excited when this girl would play MSN games with me in the 6th grade, had a year long crush on a girl in high school but she didn't feel the same and even recently before this I had a crush on a coworker that I didn't act upon because it would be awkward if I was rejected.When I was making out with this girl I was hard and when things started to get a little serious I lost my hard on and I thought in my head holy shit "am I gay?" and the summer from nightmare started. The whole summer I spent thinking am I gay? do I walk in a manner that would suggest it, do I talk in a certain way? I started to check every action I made and how I acted around men/women.Fast forward, I'm really unsure about my sexuality and I'm just scared. I think I notice men more now and even their butts, during the summer it freaked me out that my attention would be placed on a man's butt now it doesn't freak me out as much anymore.Also I used to be very nervous around girls and now I'm not which scares me even more. I've never been nervous around guys before but sometimes now I am, all of this made me a little homophobic where if my friends playfully grab my arm or something I kind of freak out I just want to go back to the way I was I feel like I can't even joke around with any of my male friends anymore because my mind would think that I'm hitting on them which I have no desire to. I'm scared to hangout with my male friends now.I'm trying to take things lightly and focus on school but this is honestly what's on my mind the moment I wake up until I fall asleep.