We are going to visit my family in a few weeks and I don't know what nappy size to order? I am looking at Pampers Baby dry and am thinking between size 5+ and size 6. I don't know what Kai weighs now, when he was last weighed when he turned to he was around 30 lbs, I am sure he is a bit more than that now, should I go for size 6 to be on the safe side?