I'm sorry you're having such a tough time with your roommates. I don't think there is a whole lot you can do about their messiness unless you have a little pow wow and agree to some rules or compromise. Being realistic though, I live with someone who is very messy and would be a hoarder if I didn't keep on top of it. I can talk until I'm blue in the face but she's still messy.

As far as them expecting you to be with them all the time...it's nice that they like you so much but you need to set some healthy boundaries and stick to them politely but firmly. Good luck and best wishes.