My baby is about to be two months and we have her in size 1 diapers currently.and they seem to fit. They go up to her belly button so I don’t think it’s to small but for the last two weeks she poops it leaks all out the diaper leg holes and leaks up past her belly button all over her . It happens every day and when I put her diaper on I make sure they’re are no gaps . Do you think she could be size 2 already in diapers? Or anyone else have some thoughts on what it can be ?