My son falls asleep while breastfeeding after a few minutes. Is this normal? And how do I know he’s getting enough milk?

My son used to fall asleep at the boob too when I was breastfeeding. What I normally did was to tickle him, usually under his chin or feet to stir him a little. Sometimes he continues sucking, otherwise if there isn't any response, I'll unlatch him. And don't worry, babies are smart little beings. They'll cry for the boob if they're hungry