Does he just want me for sex?

That is correct. Someone who loves you is not going to focus a relationship on sex. As a guy that use to be a player, I know all the games. A guy that loves you will call you all the time because you are all he will be thinking about. Also may I note that when you talk you should be able to have convo's that are not sexual based or don't tend to lead to sex/phone sex, and/or talking about having sex when you see each other. Guys are going to get mad at me for this but here is how you can tell a guy just wants someone to have sex with and doesn't take you seriously.

1. Buys you things
2. Takes you out drinking
3. Flirty things like tickling, bumping in to you in playful way (this is him testing his limits with you to see how far he can go, and you will notice he will progressively get bolder)
4. Tries to impress you
5. Doesn't answer your calls
6. Does not talk to you until late at really late at night
7. Only talks to you a few days out of the week, and mostly only because you call him.
8. He brags to his friend about you or shows you off. This is a sign that he is with you because you are a trophy to him. This is not love, this is a guy that is insecure and is with you to make himself look better or feel better about himself.
9. He is always trying to bring you to places where is friends are (he is showing you off)
10. He doesn't care to see/meet your parents/family or is scared to or says its too soon. (this means he doesn't want to do it because he doesn't plan on staying around long)
11. You catch him looking at other girls when your out with him.
12. After you have sex with him for the first time up to/after the first 3 months you see that he is not the prince charming he once was.
13. Everything is says seems like he is telling you what you want to hear, and doesn't fit how he typically is.
14. He is too flashy (who does he need to impress other than you? )
15. He goes out with out you, and says its guys night out, or doesn't want to come out with you and your friends. (this is to give him time to go out and flirt and try to get some strange)

Bottom line is the guy that really loves you is going to be the guy that you meet and think is too clingy, calls too much, tries to hard, and so on. He might not say all the right things because he is unlike other guys and is just being himself and not telling you what you want to hear. He can talk open with you because he feels comfortable with you. He might say some off the wall stuff, and you just have to try to put yourself in his shoes. Realize that he might be in need of some effort to mold him in to the perfect guy. Guys do listen and do learn when they love the girl they are with. If this guy says something you don't like, don't get upset but talk to him. If everything is great between the two of you other than some trivial things, talk and make sure he understands and iron the things out. When a real man loves you, you become his life.

If you're having a good time and don't have any commitments with each other or anyone else I wouldn't be "paranoid" as you put it. If you did have a commitment before the "sex" and you've noticed a change in his desire to see you more ,don't be paranoid rather be glad to know you make him feel good and know he wants to be with you regardless. Nobody else seems to be getting his attention

I wouldn't totally discount his behavior. Men are men after all. But it could also be that now he has the physical and mental connection with you, so he just can't wait to be around you. Beginning a relationship is so much fun! Lol

I think it's very possible he has some feelings for you; I'm sure he could find a booty call a lot closer to home! Do you do anything else when you're together? Like, go out for drinks, dinner, dancing, etc? Maybe mention that you would like to, and see how he reacts.

But it sounds like he was interested to begin with, and once you had sex, he knew for sure that you were interested, too, so he just naturally stepped it up.