I cannot thank you all enough for your kind words and support; opening up about this has been a pretty major step for me, and it is really amazing to get such a supportive response.
Since the other night I've talked to both of my parents about what's going on, and it actually seems to have gotten somewhere. My mother admitted that things have gotten way out of control and decided to stop drinking (although, for whatever reason she is not willing to admit the vomiting was due to alcohol. Just my bad cooking, go figure); she's said the same thing before, but I'm still hopeful.
Reading your responses has really made me realise how dysfunctional everything is; she's an adult, capable of making her own decisions so her problems are not my responsibility. I can realise that rationally, but I still feel a twinge of guilt when I think about it- it might just take some time. I also just need to shift the focus onto myself; I need to find a way to be okay, regardless of what she does.
At the moment, I'm not in a financial position to move out of home but I think you guys are right- I need to get out and socialise more; for as long as I can remember I've been afraid of having people come over due to embarrassment, and I have been afraid to go out because I felt like I needed to be home to take care of her.
And Mracoa, you're definitely right; I do tend to attract all the wrong types of people- I actively seek friends/partners who seem more nurturing and want to be together all the time as I've seemed to miss out on getting a caretaker, but they always end up being really controlling.
I'll keep you updated on what happens next (if you would like?) but I mostly just wanted to say thank you all so much