Is this normal?

Regs

Baby woke up at the 3 hour mark for a feed, so I got her up and she drank for about 3 minutes, gulping it down fast and swallowed a bit of air so I detached her and tried to burp. But she fell back asleep, I've changed her nappy to wake her up again but shes just still content to be asleep shes even milk drunk with her little smiles.

Should I just let her sleep? My breast still feels pretty full

She is 2 weeks 5 days