Congratulations!! The advice I got for my DS was to feed him in his diaper, and if needed, rouse him with a wet washcloth. If even that didn't wake him, then I'd let him be though. Maybe also taking a diaper change break from the feed can help.
But he was losing weight so it was an issue for us, but as Charli said, if your DD is fine weight-wise, then I guess you can just go with the flow.