Your response to Kelly was so rude it provides a big clue about the problem here.
Why on earth would you move with your bf into his mommy's home? Most moms wouldn't let this happen, yet for some reason she decided to give you a roof over your head. Did you think this meant you could call the shots?
Sorry, cupcake. You get to do that when YOU are the one who owns or rents the place, and it's YOUR name on the utilities.
Finally, you're getting your own place in the fall? Fall is a month away. You and he will be financially stable enough to pay rent and utility deposits, furnish the place, pay your own bills? Both of you? I doubt that.