What's with this guy?!

I'm (20) ,he's also in (20's) I have no dating experience or relationship experience.So, maybe it's because I am horrible anymore at telling of someone's flirting.or I tend to fall to quick for someone who's nice because of previous abusive situations but then I end up realizing it and get crushed.So this guy in my class very nice I don't know where to start honestly. Actually I'm reluctant to put it out. But it's been giving me so much anxiety as well.So it all kinda started 2nd day of class he came in kinda late and sat next to me. wasn't prepared so I shared. We then introduced ourself blah blah blah.he then decided to sit behind me. Which really sucked because I thought he was very interesting and wanted to know more about him. The only problem is I can be very shy and fearful when it comes down to it. I'm very outwardly confident but on the inside I'm a coward when it comes to crushes;but then again i live in the south. He over the semester has been very flirty and nice. And I can tell if he's just a super nice guy or genuinely interested in me.I say this because he stares at me a lot, granted I look at him too. But it's different and smiles like how when white people like girls smile with all their teeth showing. There's other little things like his feet and legs are always extended towards me like as if to say I'm far away but this is mine. He will act uninterested one day but the next will be all over me flirty. Smiling subtly flexing and what he started recently the man spread. He pretty much makes sure when I look over my shoulder I see it. The first time I did I was embarrassed bc my eyes when straight for the crotch and he knew but smiled and not like a weird creepy smile like cute smile. I shrugged it off bc straight guys do this shit to me all the time but today when I sat on the other side of the room his whole body was facing my direction and when I looked over he was starring at me dead on and of course the man spread.My thing is I can't tell if this person has genuine feelings but is holding back or if it's me! Any help would do sorry for one of these stupid is he or isn't he posts. Just need to vent.Thanks