This is one things I really dislike about disposables, not knowing when to go up a size. I like to buy the big box of 204 diapers and we are currently using size 2. LO is 5 months old and only weighs about 14.5lbs. I dont know if I should get another box of size 2 or if I should get size 3. I hate when the diapers get tight on her half way through the pack. I bought the size 2s before they fit her properly and they were huge on her!