Is any one using Avent bottles? I read people say they leak can u tell me if anyone has had problems with this? And what size teat are you using for a 6.5 month old. I am currently using Dr browns but my baby's colic has gone now and fed up of washing all the funnels and rubber things what comes with this haha I was thinking to switch to Avent just wanted to know mums advice on these :-) thank you.