Am I wrong for wanting to move out?

I'm 21 and I've been with my boyfriend, who's 23, for a year now. We live about an hour away from each other and gas and eating out are sucking us dry. So we decided we're ready to move in together (or as ready as a 21 and 23 year old can be). I've done the math a thousand times, and on paper we would be fine every month. I realize that things do happen and we could be broke, but that's just a risk I would take. I'm still living at home right now, but my house isn't exactly comfortable or relaxing. I've got a two year old niece and a two year old nephew who are always there and constantly get into my stuff. In the past month they've torn pages out of a book in my room, smeared poop on my bed, left dripping bottles on my bed and on the floor, smeared hand sanitizer everywhere, and a whole list of other things. I do close my door any time I leave my room, but they know how to open it and I don't have a way to unlock it from the outside. Anyways, my main reason is I just want to be with my boyfriend. So I let my mom know I want to move, and she hasn't been speaking to me since then. My older sisters moved with no problem, and I had a lot of time to mature last year because my mom went to jail for most of the year for her habitual pill addiction and theft, and I played the mom role while she was gone (cooking for and shopping for and cleaning up after my dad and brother). I also spent the past four years managing my family's finances. I haven't told my dad yet because I'm terrified of what he'll say. I asked my mom this morning if she was mad at me, and she said she was upset at what I want to do and she'll hate my boyfriend until he dies, and I don't need to go shack up with him because I'm better than that. I guess my question is am I justified for wanting to move out? My family also doesn't like my boyfriend very much because they think he has an annoying personality. Sorry for the really long explanation...