Why do I feel like my gf (17F, bi) is cheating on me (17M, straight) even if I don’t have any real reason to think so?

r/

So for a bit of context, we met at school, more specifically on a school trip to Europe where we started talking, but as friends. When the trip ended, we kind of stopped talking for about a week, until she started to text me a lot.

She is my first girlfriend ( I am 17M), and also my first talking stage, so I had no idea how to handle it properly. She had a lot of past experiences, with 3 relationships that I know of that went to intimate moments, ( and possibly more since I don’t have to courage to ask her about it because I’m scared of her answer).

So I started to really develop feelings for her and she did too, so we became an official couple in June. I took her to prom and everything was going perfectly. Then summer started and she started working a lot. Like 70h weeks. At first I was like, ok that’s fine there’s nothing wrong with having a job, but then when we finally had time together she would always talk about her work drama, and about one guy in particular that was causing a lot of drama by sleeping with like almost every girl at their workplace (some small golf course restaurant). Like i know it’s not something big but I still felt sick when she would mention his name.

During the summer, other than that I don’t really think that there was anything else, but I started to think that every time she was at work, I was imagining her and him talking and other stuff and I kept of feeling really sick because of that even if I kept telling myself that she isn’t like that. So now, we both started at new schools since we moved on from secondary school ( I’m in Quebec so the education system is different than in the us, so we are both starting CÉGEP, which I think is like the equivalent of grade 12? I’m not sure), and we both went to different schools, and this is where my main concern is.

She keeps on telling me about all the friends she’s making, and it’s all guy friends. Like she’s telling me that she eating one on one with a random guy she met in a class, and that she’s in some friend group which is almost exclusively guys. Like I’d say she made about 10 friends and like a solid 7 of those are guys.

I just don’t see why she wants to talk to guys if she already has a boyfriend and I don’t know how to tell her what I think about it without being seen as controlling or insecure. It’s really starting to affect me a lot because it’s my first relationship and I have to idea how to handle anything like that.

It seems that I forgot to mention some important details:
1- she is bisexual so idk if it changes anything but it’s a good detail to say
2- she had 2 other guy friends from before we met ( i completely trust those 2 because they are good friends of mine and we knew each other before they knew her)
3- I don’t think that the problem is anything sexual, I would say that she enjoys our intimate moment a lot and she doesn’t have any problems with being satisfied
TL/DR: Just want some advice on how to handle my girlfriend who has almost exclusively guy friends