Mom "refuses" to let me move in with my boyfriend

I live with my mom currently with my 10 month old. We are moving to a new house and I know my mom wants me to move with her and help pay bills (which she can easily do on her own).

I've been dating my boyfriend for 6 months now and would love to just move in with him. For the last 3 weeks I have spent at his house I have been happiest that I've been in a long time.

Relationship with my boyfriend is serious as in both him and I are planning our future together and planning to move back to Texas where his family is.

My mom keeps asking me what I'm going to do when he goes back. She knows I want to go but I don't understand how she thinks she can stop me.

I love my mom but I'm 21 and have a 10 month old. I make my own money, own my own car, care for my son my dog and myself all on my own.