  I grew up in San Bernardino, CA and my two siblings and I were raised by our mother. We were very poor, and I don't remember a time when we were not struggling to make ends meet.
My mother never married...she dated here and there but nothing was ever really serious. I mean things were tough for her but she made it seem like there wasn't a worry in her mind. Right now I don't have any children but I have a friend that is doubting her parenting abilities with her kid because she and her lover fight over responsibilities and discipline and stuff like that where the kid is concerned. So while she was telling me about the problems, I was afraid to offer any hard advice because I did not feel that I was experienced in this area. However, after thinking about it today this is what I probably should have said on the phone... Firstly, I think you are a good parent. You have raised this kid practically by yourself for her whole life. Yes, being a single mom is hard but being a mom in general is hard as well. Raising a kid is not supposed to be hopscotch and ice cream parties; and then to add a lover in the mix that wants to have say in how you should now go about raising your kid is a lot to handle. My points are these I guess... For one thing, no matter how well a person is brought up, unless they are parents themselves they have no clue how to raise a kid. I mean, just because I work with kids and love them, doesn't mean that I know jack about how to raise one in my own home. Then, I have to say why now are you doubting yourself? You have been raising this kid (whom I might add, is topnotch compared to some of the little assholes I work with) and now you choose to doubt yourself when you get into a longterm relationship.
You are the one that knows how to be a parent because you have lived through it. You should be telling her what she is doing wrong and how you expect your child to be disciplined, treated, and ....I don't know RAISED. It would be easy for me to step into any parents life and tell them advice based on what I have "seen other parents or my own doing," but I would be speaking as an outsider trying to get in. And that's what I think is happening with this situation. 
