Maybe he's just not that into me... should I give up?

[CRAZY]

I'm in college, 18 turning 19 next month. I've been talking/dating this guy ever since the end of October. We would spend a lot of time with each other, like going to the dining hall or somewhere to eat, or going to our school's arcade, and he'd initiate the plans 90% of the time. Sometimes we'd study together. He has introduced me to his friends, even his sister. Sometimes he'd prefer hanging with me than with his friends. Over break we've video chatted or talked on the phone. And every morning, he'd text me saying "good morning", and we'd talk all day. Always includes me in his future. We've talked about relationships before, and he did mention that he likes me and we're "talking". He seems genuine.
But then I'm very confused. He has a few female friends, which I don't mind, but sometimes they can be flirtatious with him. And whenever he talks about them, he just says "this girl" or "one of my friends" instead of saying names. He also still talks to this girl he dated before me. Twice on Twitter, he mentioned about the disappointment of the lack of "a certain type of girl" (won't say the type) in his town. When we used to hang out, he'd be on his phone or he'd always yawn (which I kinda understand, because he hardly got sleep at night). Or if he'd invite me over to his room and it's only us two, somehow we'd end up making out, and sometimes right after he'd get sleepy... but then he offers for me to sleep over his place.
So basically his actions say he likes me, but his words don't follow up, if that makes sense. I question this now because last night he was taking long to reply, I go on Twitter and he was replying to others. Advice?