New school and there is drama already?

I moved over the summer and started at a new high school in August. At my old school people knew I was biual but I'm not too keen on people at my new school knowing. Because of a messy break up and lots of heartbreak along with serious confusion, I decided that I didn't really want a relationship anytime soon. Unfortunately I'm a very dependent person and I love being in love so I've had an open mind with people. There's a guy in my JROTC period, "Chris", who clearly likes me and has already asked me out however I told him to give me some time to think. Chris is a great guy but he's a junior and I'm a sophmore and he is also my subordinate as far as rank goes (dating your subordinate is sometimes looked down upon but it doesn't really seem that way in my school from what I can tell). There's also a girl in my JROTC period that likes me, "Brianna". Brianna has a boyfriend but her and Chris flirt all the time, which makes me doubt that Chris would want to go out with me. But Brianna says that it's just playful flirting and I kind of believe her. Before last night I had no idea that Brianna was or that she liked me but Chris told me that and it was also confirmed by another cadet. That's when I started to notice that Brianna would always sit/stand next to me or find excuses to touch me. And now I have no idea what to do. Should I go out with Chris? Or should I confront Brianna about liking me? I wouldn't want to come between Brianna and her boyfriend (though she talked like she might break up with him soon) but should I see if anything could happen between us? I need any advice that can be offered.