Bottle strike?!

So it's been 2 weeks of my 5 month baby having less and less formula.

She would usually have 4 feeds a day of 7 oz, 4 hours apart. She is now having maybe 1 oz for the first two feeds and then 5 or 6 for the other two.

I'm keeping distractions to a min. She has never refused milk before.

Today I gave her a tsp of baby porridge and she had that (and no milk) kind of.

She's having less wet nappies now ofc. But she is playing and babbling as normal?.. I got her weighed about 2 weeks ago and she was right on track for her percentile but now I am starting to worry.

Surely it can't just be teething..