How about giving yourself a personal time limit?
On one hand you really want to know where he stands for the future, on the other you want to give him some time to know for sure. You also know you can't do this forever, but don't want to be nagging or pressuring him in the meantime.
It seems to me that a good compromise would be to define for yourself what you consider a reasonable time to stick around. Some blend between what you can handle and how much he needs to be sure. Maybe with some kind of endpoint, you can feel comfortable putting the issue on hold and really enjoying things as they are now without feeling like you are wasting your time or being jerked around.
By the end of it, you both will likely be seeing things from a different perspective and with a lot more information to make a decision with.