Wait for a quiet, low-key time when you are together and say something to the effect of, "Do you remember two months ago when I shared how I felt about you and we agreed to get to know each other?" (Wait for acknowledgment.) Then ask, "Are we ready to make it official yet?" The best way is to be direct and to find the right time -- where you're alone, have enough time to talk, and the emotional tone is right. I have a feeling this is going to go well for you given how well you've gotten along the last two months.
If you have trouble with how to make conversation "transitions," try this simple trick. Just say, "I have a question." That gets their attention, the other person goes quiet, then you can ask away. Good luck!