My mother is a child.?

I am the sort of person that is tidy, organised, responsible, RATIONAL and realistic. My mother is not. She is irresponsible, messy, untidy NOT rational or realistic. Don't get me wrong she doesn't take drugs or go out late or anything (in fact most of the time shes by herself) but she acts like a child.

She spends money we don't have..like she will blow heaps of money on a tv she DOESN'T need. We don't have money to throw around as she's currently quit her job. Seriously, she has NOTHING saved in the bank, she used to spend everything she earnt when she was working.

My house is a constant pig sty. She buys crap all the time which fills out the whole house with junk. I live in mess and have most of my life, I attribute this to the reason I developed OCD actually.

Just today she decided to get faster internet (at no extra cost) but the time she invested in calling someone to come up she could have invested in calling a plummer as our sink is broken & we can't really use the hot water..its winter :/

I don't mean to complain. I am a spoilt person and I don't treat her with a lot of respect. This is due to her letting me walk all over her with no discipline. I take the blame now as I'm 21 so I've began mending my ways and acting more like an adult. Its hard when you've been brought up with no discipline or punishment.

I love my mother a lot, I do not blame her for anything. She was a single mother and she did the best she could. I am glad she is my mother. But I am endlessly frustrated that I feel like I'm living with a child making the decisions of the house. I don't know how to handle this frustration. If I tell her she either tells me I'm acting like her mother or agrees but still does nothing to change.

I'm not asking you how to change her (becuase shes going through a lot atm) but I'm asking how I can approach this situation and deal with the stress and frustration its causing me.

TY :)