Hi there,
So if I'm correct she is now drinking a little under 20oz formula per day? That is a bit on the short side. You would want her to be getting between 20-30oz plus some dairy with solids, although I think ideally 24+oz would be best.
I think that with bottle feeding many moms will drop down to 3 bottles around 9mos, but that doesn't mean the quantity drops, just that they are consolidated into 3 bottles rather than 4.
Milk intake will start to decrease after 9mos as LOs eat more solids, but it should be a gradual increase and I would say before 9mos you really want her to maintain the proper amount of formula.
I would see if you can back off on the solids just a little to get her drinking a bit more formula again. But it does sound like she is doing great, and remember too any dairy in her diet (i.e. yogurt or cheese) will count towards her milk intake as well, so since she is eating that stuff I wouldn't be too worried if some days she doesn't drink much more than 20oz.