4 month old with a weak suck...takes forever to finish the bottle

My 4 month old takes forever to finish a bottle. She ends up tired and then doesn’t drink more than 2oz. I’m getting concerned.

I changed the flow and that helped a bit...she was in the Nicu for a few months and wasn’t able to suck until 2 months old. I’m wondering if that’s why and she just lost her suck. I’m so so scared about needing a feeding tube.

Anyone else experience this? Anything that helps?