Why is my 5 month old waking up more often?

My baby is 5 1/2 months, and she started waking up more often. Before she would have one sleep stretch of 5-7 hours, then she would wake up every 2 hours after that. Almost 2 weeks now she wakes up every 2-4 hours, depending on how much she feeds. For example, if she woke up and only ate 2 oz, then she'll wake up after 2 hours. If she only ate 3 oz, then she'll wake up after 3 hours. She drinks 4 1/5 ounces max, so when she drinks that much she'll sleep around 4 hours.

I don't know what it is. She used to have a sleep stretch of 5-7 hours as I said before. She already went through her sleep regression. At least I'm pretty sure because she used to wake up and be up a lot when she went through her regression.

I miss her long sleep stretch! I keep waking her up with the little sounds I make when I go to bed too (she sleeps in her crib in my room).

Help 😩

UPDATE: tonight she woke up every 2-2.5 hours no matter how much she ate. 😖