Am I bisexual or am I just trying to fit in with my gay friends?

Your sexuality is entirely your own, it cannot change because of other people, but it's possible that hanging out with gay friends helped you see a part of yourself that you didn't know before. Try to analyze your emotional and physical responses to fantasies with people of different genders and see how that makes you feel: that will give you the answer you need! Feel free to take all the time you need to determine it.

This is a question ultimately no one else but you will be able to answer. It's okay to wonder whether you are actually interesting in something (or someone!) or whether you're merely trying to blend in. Of course spending time with gay friends will not make "the gay" rub off on you like paint. What can however happen is you paying more attention to people of the same sex than you did before. Then you might notice a select few (who you previously would have ignored) actually make you feel excited. So, there. Maybe you're bisexual and only just realized. Or did you only find them attractive in an aesthetic way? Maybe even just because your best friend has a crush on them? Suddenly you worry your feelings aren't valid. You don't want to be the person who only follows the latest trend. First of all: your feelings are valid. Whether now that means you're bisexual or not. I can't tell if you are. Nobody here can. Arousal and excitement about a person of the same sex gives you a hint, but what actually matters is, do you want to act on that arousal? How do you feel when you imagine getting sexually or romantically involved with a particular person? Note that bisexuality doesn't imply you're suddenly attracted to everyone. Just like you have your preferences in people of the opposite sex, you're going to find some of the same sex amazing and others repulsive. It's also possible you only crave sex with men and long term relationships with women, or the other way around. What feels good for you? What feels right? Do you want to explore your sexuality? Flirt with someone you normally wouldn't, but don't go any further than that? Do you want to know how it feels to kiss or sleep with a person of the same sex, or are you afraid deep down your friends might consider you boring if you always stick to hetero romance? Only you are able to figure out who you are. If you think bisexual describes you, then you can rightfully say you're bisexual.