Whatever is happening now is as good as you will have with him. So, it sounds like what you have is FWB and that is the way it will continue or it will just end altogether because one or the other will end up finding someone they can have more with.
I knew this guy for over a year. We talked a lot on the phone and IM. He always wanted to know what I was doing and we really had some cool conversations. He was smart and had a great sense of humor and we hit it off in our calls. We did not live that close to each other but we did make a point to see each other here and there, though not frequently. Each time we did, we had sex.
So, after a year of this I was at a crossroads of wondering if I should stick with this guy or start dating someone else. I had to finally put it on the line with him. Guess what, he still did not want to be straight with me. He said a relationship was a lot to consider because we did not know each other that well. OMG, we had been talking and hanging out for over a year. So, I told him I was going to see other people and he really had nothing to say to that. He kept trying to contact me and talk as well as throw in some sexy conversation, but I ignored the sexual stuff and kept any other comments brief. I have a boyfriend now and I finally told this guy (since he wasn't taking a hint) that I could not talk to him anymore as I felt it was disrespectful to my boyfriend.
If a guy wants you for a girlfriend or a relationship, they ask. If they like you for conversation and occasional sex, they do that instead. A lot of guys are perfectly happy having what you describe without ever wanting more with you. Sometimes you can be really hurt to find out they end up moving on to another girl and having a relationship with her because she meets their idea of girlfriend material. It is a bummer how many girls will continue in a FWB hoping for more and not getting it.