How do I ask the guy I’m seeing what we are?

Why don't you share with him what you've shared with us, here. Its as good as any alternative. Be prepared to also include what you want from the relationship.

The best approach is always to hint to him that you want something serious as opposed to asking him. For instance, doing things like talking about couples goals, telling him how happy you are around him and asking him about your feelings are all great ways of hinting to him that you would like a relationship. Guys are not clueless and he will more than likely pick up on these vibes that you are sending. What you can also do is use the setting to your advantage as well. For instance, if you tell him these things that I have mentioned on a date night then they will have an even more overt effect than if you simply just told him in a casual setting. Good luck and I hope this helps :)

That's a long time to be dating someone without knowing if it's a serious relationship or not.  The only way to really know is to ask him.  It's not rushing the relationship and it's ok for you to want clarification on this.