Need help!

So I've been "homeless" for almost a year, but I stay with my grandparents. It'll be a year in June. My mom is trying to save but not really trying. Her husband couldn't give two fucks what we do. My brothers miss having the family in one house. I miss having my own space. I live in the living room while everyone else has their own room. I talked to my boyfriends dad about my situation who has known me since I was like 6 he has 3 extra rooms an offered me one once I turn 18 in July. He said it would 100 a month as long as I'm in school, respect his rules, and did my part around the house. Which I can do no problem. My boyfriend would probably come stay there too. My grandfather said that's not a bad I idea. He said as long as I know I can keep up my part of the deal with him an that me an Tre can work out its a good idea. I get to be on my own an learn responsibilitys from a trust worthy person. My grandmother thinks it's a super bad idea an that she'll just clean her extra junk out of one of the extra rooms in her house but she's supposed to been done that last year for me. She hasn't done that yet. I know my mom isn't going to like it. What do you think? I'm so confused on what to do because I don't wanna leach off my grandparents all my life like my mom is doing I want to be on my own an make it on my own and I'm being thrown that option.