Breastfeeding and going back to work

Alesia
So starting with the details I have a 7 week almost 8 week old little girl. I went back to work when she was 5 weeks old exactly because we couldn't afford for me to miss more time. It took me about 4 weeks to just get my LO to even nurse before I went back to work. She had nipple confusion, then was a lazy nurser... then she finally was taking the breast and getting full. Well for the last couple of days she doesn't want to eat when I bring her home from my mothers. I give her my breast for 2 minutes and she just sucks on my breast like a pacifier and then doesn't eat for 3-4 hours. She isn't eating, she doesn't want to eat and it's really upsetting me. I think it has to do with she doesn't even want to try, because my mom gives her any expressed milk for the day, but has been resorting to formula because I am not getting enough milk she says. ( I get about 5-6 oz in a 6 hour shift.) I've told my mom several times that LO doesn't need 3-4 bottles while I'm gone for six hours, but my mom feeds her that anyway. Then complains that she's throwing up too much so gives her more. I could feed LO before I leave and my mother will still give her a bottle an hour after I just fed her and then every 1.5 to 2 hours after. I've tried to tell my mom that she's feeding her too much (3 to 4 oz every 1.5 to 2 hours) but my mom doesn't believe me, and swears up and down that she's "starving". Which I will mention when she was decently nursing she only was hungry every 3-4 hours. So it makes me think she knows now that she gets fed more with a bottle and won't take my breast anymore. Any suggestions on what to do?
EDIT: I would like to add that before I went to work I pumped 6 full bags of milk and they are all gone now 😑