Very bad idea. Get ready to lose all of your privacy. I tried it when I was 22. It only lasted 3 months before I got totally sick of her Mom's BS. Will you be sharing the kitchen and bathroom?... that will make things even more difficult. Trying to prepare my meals was a fuckin nightmare. She'll expect you to wash all the dishes right away and keep everything clean and neat.
It might work if you are tolerant, but you should prepare yourself for her Mom to be up your ass all the time.