Tommee yippee teats collapsing

[HaychEss]

I’ve bought 2 new packs of tommee tippee medium flow teats (size 2) and each time my baby is feeding in them they collapse straight away. Does anyone know why this could be?

I think, may be wrong but could be trapped air. They have a circle on the side next to the teat. Unscrew the lid, squeeze that little circle then screw lid on again keeping that pinched. Then let go, it allows the air to flow through. Failing that could be wrong size for age of baby? Hope that helps

How old is your baby?
could be clamping down on them to try and control a fast flow?

Will give this a try, thanks

2 and a half months, moved up a teat size as she’s on Gaviscon which thickens the milk and wasn’t allowing the milk to flow from teat.