Your BF is only 21! The brain doesn't stop developing until age 25. Most guys are a few years behind us in maturity development. I get it you have a list of I want it now, and I need this for my future. Relax. Focus on your own goals but don't get so caught up in it.
This won't be your last relationship...you will probably be dating and having experiences. What's the rush anyways? Let it go...leave your BF alone, it's his life, he will evolve into something someday, but that's not up to you. As for your mom, let her comments roll off your back. You don't need threats like that. You are not going to die old and alone never having married.
It's way too soon to fret over this. Take a break, go on a trip together, have fun, explore different cultures, or take up a new hobby together. Everything will work itself out in the wash.