my dog gave birth on monday its now friday and i worried that the pup isnt eating enough she seems healthy enough and got a belly,there was only the one pup iv made sure the nipples are producing milk,she seems to feed for 5 mins then back to sleep for and hour or 2 then 5-10 min feed max and sometimes cries when feeding as if not getting any milk, is this normal i was told they should feed for at least 15 mins every 2 hours,she has grow a bit in the first 4 days