I think we must have the same mother! Same stuff here. But as a mother of a 25-year-old, I also see this from both sides. I really work not to become my mother. When my daughter moved to Canada, I helped her pack!
Anyway, my mother has always been a nightmare about such things, but the funny part is, when you think about it, people like this are quite controlling and manipulative. I mean, a caring mother would want her children to have the best in life, no matter where it leads. Your mother doesn't want that for you, and mine didn't. They wanted what they wanted for their own selfish reasons, with no concern for what would make us happy.
So, the last move (okay, not the move to the UK, but the one across the US for grad school before the UK), I literally called her as we were driving out of the state, and left a message: "Hey Mom, I'm moving to Arizona. We're driving now. I'll drop a line when I arrive later in the week."
I think she got the message -- let me live my own life without commentary from you, or I will simply exclude you from any discussions about my plans.
So, when I got ready to move here, I told her that I'd had a job offer, and would be going in 4 months. "How wonderful for you, dear!" When we take control, we teach people how they can and cannot treat us.