We have had same problem would leak all the time would be teats or the bottom not done up properly. We have actually just changed bottles bur due to colic now have tommee tippee instead x
How are you making up the bottles? There’s a reason I’m asking because if you do it a certain way they do leak! 🤣
The first time I made mine up I hadn’t clicked the teats in properly could it be possibly that? x