What is the best retirement plan for an unmarried stay at home mother?

I am a 28 year old stay at home mother, who is not married. I am concerned about what this is doing to my retirement savings. I want to know what my options are to be prepared for retirement.
I forgot to mention I do not receive any assistance (e.g. welfare). I do live with my boyfriend, who is my daughter’s father.

Since you have no earned income you can’t get a plan like a IRA so you will need to invest in taxable accounts. Since you don’t have earned income you are probably not even paying taxes unless you are living on investments. If you are on welfare you might not be allowed to have assets so would need to wait until you got off welfare to start saving.