Looking for guidance, EBF now almost exclusive pumping

Daughter is 16 weeks tomorrow

She took almost 3 weeks to gain her birthweight back and was slow gaining after that. I was EBF. My milk came in like WOAH and I had a ton of milk thanks to the hakaa in the freezer. Because she was not gaining, the doc had us supplement with pumped milk in a bottle after nursing. She would take it pretty much everytime and drink 1-2oz and then just chill.

A few weeks ago, I filled the supplemental bottle with 4-5oz and she drank it all. For the next feed that day I pumped and got ~1oz combined. I started assuming she wasn't getting enough at the breast since she would nurse for 30-40min and then take 4-5oz from the bottle. From that day on, I started almost exclusively pumping and feeding frozen milk stash.

I am still getting ~1-2oz at each pumping session (6am, 9am, 12pm, 3pm, 6pm), with the exception of a 4:30am pump where I can get ~6oz. She is taking a 5-6oz bottle at the 5 times noted above. I can sometimes nurse her in the morning, but she will still take 2oz or more after a 25 min nursing session.

I don't mind this setup during the week since I work full time and half to pump anyway, but the weekends are killing me. I am planning to schedule a consult with a lactation expert to see if her latch is the issue, or something.

At this point we are running through my frozen stash waaaay faster than I can replenish with my pumped milk. Because of this, we are really just trying to get to 6 months with only breastmilk and then introduce formula out of necessity. I am hoping to be able to keep the 1 morning nursing session for a year, but she seems less and less interested in it since we moved to a medium flow nipple on her bottles.

Any advice or suggestions on what to do? I want to do another experiment this weekend and try to nurse her for every feeding session and offer the supplemental bottle after to see how much she takes. My thought is that if she takes more than an oz or 2, nursing for 30-40 minutes and then bottle feeding 20-30 min is a waste of time v pumping.