I've been breastfeeding my 8 week old baby and have recently started giving him one formula bottle at night. He slurps at both and can't seem to get a good seal. He had trouble when he was younger but then had two good weeks of perfect feeding and has now started this. It is like a clicking/sucking noise. I've googled it and it mostly talks about over active letdown which isn't the issue at all. Please help! It is hurting quite a lot and I'm on the verge of stopping breastfeeding all together.