anyone have gassy babies? he's 2 weeks old and really strains and fusses when he's trying to poop or get gas out. the only thing that has helped is gripe water. he is fed pumped BM from a bottle..we use Nuk..supposed to be good for colic, has an air vent and is a slow feeder so I hope it's not the bottle. just wondering if anyone has any tips. thanx!