Breastfed baby slow weight gain?

My daughter had her two month appointment two weeks ago and lost 4oz. She’s exclusively breastfed. We had a two week weight check today and she’s up 6oz. I started chugging water and oatmeal and was forcing her to feed more often and for longer per the doctors recommendation. The doctor said she didn’t gain as much weight as she wanted her to, so now we’re supplementing formula after feeds. She’s barely on the weight curve.

But she’s not hungry! She eats great, doesn’t cry constantly like she’d be hungry, or feed for long periods as if I’m not producing. She’s ahead developmentally and grew two inches since her two month appointment, she just can’t keep weight on her. And it’s stressing me out something fierce. I’m worried something is wrong.

The doctor said her newborn screens were normal but if she doesn’t gain more by the next two week checkup we have to do blood work to see if something is medically wrong. She sleeps through the night and engages while she plays...she just isn’t gaining a lot. Doctor said no solids yet as it’s too early, but I’m getting scared.

Has anyone else experienced this? This is my second breastfed baby and I didn’t have this issue before. She was over 8lbs at birth but weighed in the 8th percentile at my anatomy scan. Hoping for some mom support...