my mom wants to get legal guardianship of my baby

I am 17 years old and i have a 4 month old baby girl, her name is Lacey. My mom thinks i am an “unfit” mother and wants to get custody of my daughter. I graduated early and got a job so that i could provide for my daughter. I work at a daycare so i also have free childcare. I give her baths whenever she needs them and i feed her. She’s never wearing dirty clothes, have a dirty diaper, and she isn’t dirty. I hardly ever go out, i have maybe gone out 3 times since she was born. The father of my child isn’t in the picture at all which makes me a single mom. I’m really scared that I will lose custody of my baby. what do i do?

the only reason i think she could possibly get custody is that the dad and i used to fight with my daughter in the room. he would hit me but i kicked him out right away and haven’t heard or seen him since.

i moved back in a month ago, i was living with my grandparents