How do I know if he wants to be with me?

First of all, I have been out of the dating scene for a while so I'm not sure of all the "rules" anymore. Such as how often should you see each other/talk to one another on the phone, etc.

But my problem is I went on a date with an ex that I hadn't seen in a long time and to be honest I don't remember why we even broke up.

I did what you're never supposed to do on a first date if you want it to turn into a relationship. I slept with him.

However I don't regret it. We have been on a few dates after that and I have only slept with him one other time.

But I always have to be the one to call him and suggest things except for the last date we went on. And I don't talk to him except for an average of once a week.

So my question is, how do I know he wants to be with me or if he is just after sex or if he is just really laid back?