Feeding Issues

Moms, I’ve been formula feeding since our LO was born, I did do colostrum while in the hospital but didn’t BF while home. Recently it seems like our babe is struggling to eat, it’s like she has no interest in it. She gags on the bottle and will only drink an ounce or two before flat refusing anymore (she was drinking 4oz every 3 hours prior to this). We have tried different bottles and formula and nothing seems to be working. She is 10 weeks old and over 12lbs so I’m worried she’s not eating enough based on her weight. Any advice or anyone going through this too?