Is this normal or silent reflux?

Sorry if this is a bit long. I appreciate it if you read the whole thing.

My 3.5mo daughter has some unusual eating habits going on. Back at the end of September, we switched her to a size 2 nipple because she was collapsing the size 1s and had increased her intake from 2-4oz to 5-6oz. She did okay with it for about 3-4 weeks but then started vomiting after feedings.

We do burp her regularly and didn’t have any issues with this kind of spit up before, so I switched her back to size 1s thinking maybe she was just eating too fast.

She’s been back on the size 1s for about 2 weeks now and the first week, everything was okay. The vomiting had stopped but Friday we noticed that she makes “smacking” noises when she eats, like she can’t get it fast enough, and was still collapsing the nipples on her bottles. THEN yesterday, she pretty much refused to eat all day. She woke up at 7:30, took one 6oz bottle around 11am, then another 6oz bottle around 7pm but that’s all she ate all day and she sleeps through the night so she only got 12oz in a 24hr period.

Today, we switched back to the size 2s hoping maybe she would take a little bit more but vomited again this morning (around 8-9) after a 4oz bottle. She did drink another 5oz around 11:30am and didn’t vomit but I’m pretty lost on what her deal is.

She’s pooping normal, having wet diapers, her sleep is okay, she’s a LITTLE fussier than normal but she’s also teething, so I don’t think it’s related, specifically. We just don’t know what to do.

Is it reflux? Should we change bottle brands? Is she just decreasing her intake for a day or two? We plan to fall the doctor tomorrow but I didn’t know if anyone on here had any input/advice.

TIA