It sounds like your boyfriend and you are the adults in this situation. Your mother is clinging to you, and I think she is deeply envious of you. It looks like you are on your way to having all that she has not managed to have. She's kind of pitiable, but you have to be careful not to wind up revolving your life around "managing" your mother. She is more than a little disturbed and probably should be seeing a psychiatrist.

When I was 12, "I was babysitting" 3 younger siblings when my parents went out for a bit of socializing. Do not put that vehicle in your mother's name. She didn't buy it and has no claim on it. Your relationship with your boyfriend is kind of a wedge between your mother and you, and I would say it is the best kind of a wedge - like a protective buffer. You're lucky to have this guy.

Since you seem mature, you may find yourself in the position of feeling concern about your 12 and 9 year old sibs, especially the 9 year old. It sounds like they are in the custody of a "child-woman." Losing that home is terrible for your mother, I'm sure. But, if she can't afford to keep it, then that's the reality she has to adjust to.

It may be pre-mature for you to move out bag and baggage from your mom's place. I would advise you to have an engagement ring on your finger before you do that - or - have the means to totally support yourself. At the same time, you can set some reasonable limits on how much your mom can dictate. (You have to take into consideration the extent to which you are financially dependent on her.) You've only been with your guy a couple of years, and you're real young. Maybe he is the one, but it would be good for you to finish school before making that decision.

Legally, no cop is going to come and fetch you back to your mother's house when you are "missing." The cops wouldn't even do that if you were 16 years old.

Having lost your father as a partner, your mom is clinging to you as the one competent person she thinks she can lean on. She's a sad figure and this may be just the start of many years of worry you will have over her. Do the best you can, and maybe plan to spend some quality time with those sibs, as they are in danger of coming out of this damaged and causing you, perhaps, years of worry, as they develop problems. Good luck. Your thinking seems pretty straight to me.