Firstly, I'm sorry you are dealing with this. I have been through similar myself and found it very difficult to deal with.
A little about what happened with our baby - having seemingly nursed normally for the first two months of life, she suddenly started to refuse feeds. First one breast, and then both. Very quickly, we had a full nursing strike on our hands. Apparently they rarely last more than a few days. Our first one lasted a month. She would scream and fight if I so much as put her into a nursing position, and she ended up taking all her feeds as dreamfeeds, because that was the only way I could physically feed her ... which was exhausting.
This behaviour occurred on and off, a week here and a fortnight there of utter misery, followed by a few days where she seemed ok and would accept the breast when I offered. And then it was back to square one again - total refusal and dreamfeeding.
We have never identified the cause for sure, though we do know she is prone to silent reflux (not severe) and her strikes tended to correlate with periods of dodgy gastric activity - spitting up more, lots of dribbling, trapped wind, hiccups, weird gulping as she swallowed her spit-up back down, etc. So there's that, though we don't know what caused it to flare up and then die back down. Our baby also had a previously unidentified posterior tongue tie cut at 4.5 months, and about a month after that, things did start to improve somewhat.
When you say your baby has reflux, what kind of reflux are we talking? Silent or spitty? Is your baby obviously in pain from the reflux or not too bothered? Is she on any medication for it?
When faced with the bottle, how does she refuse? Does she become distressed and fight and cry, or is she just obviously not interested?
I ask all this because if your baby is obviously suffering distress from the reflux and panics when she thinks she has to eat, then the reflux is almost definitely the issue and to help her learn to enjoy eating again, she will likely need medication. If there is no evident pain behaviour/panic and distress when it is feeding time, then there might be a different reason altogether.
Eating 4 oz at a time is not necessarily a bad thing - this amount has kept your baby up in the 90th centiles! - so it has obviously been enough for her body to very much maintain itself. However, you are concerned that her intake has dropped. With reflux, babies in pain often learn their milk 'limit' and refuse to take more. This could be what is happening to your baby. I personally don't think 4 oz can have been her milk limit if she was gaining so well on that.
You also mention her lack of appetite. This one particularly worried me with my daughter - once her rooting reflex disappeared, I hadn't a clue when she was hungry, as she just NEVER SEEMED TO BE. I am quite certain she would have gone all day if I had let her; it was baffling. This, as I understand it, is also a common behaviour among reflux babies.
I hope some of this can be helpful in maybe identifying whether reflux is likely to be the culprit in your baby's case. Sorry I've gone on a bit, lol.
The good news is that my baby has gotten so much better as she has grown older. She's now eight months old and it's been two months since we had a nursing strike. Plus, her silent reflux symptoms rarely show themselves any more, which is great. She still doesn't do any of the classic things you want your baby to do, as a mother, to show you that they are hungry! Lol. BUT, she no longer freaks out at the sight of a boob - in fact, she gets very excited, and it's so nice to finally feel like she actually WANTS to nurse. I feel more relaxed about things now - even if I feel like she hasn't taken 'enough', I don't try to push her to take more as I'm trying to trust that she knows what she needs better than I do.
Starting solids has really helped too. We started at 5.5 months.
I am sure things will get better for you eventually, but it is SO hard and of course you need to find a way to help your baby feel happier about eating and lessen the burden of worry on yourself. If she isn't already on medication, then I would speak to your doctor about trying something if you feel that pain is the cause here.
Sorry for the essay! If you have any questions or anything about our experience then I will answer.