We've been at it for two months and the baby is constantly putting his…

We've been at it for two months and the baby is constantly putting his fingers in his mouth and sucking on them very satisfyingly ? Straight up smacking-smacking. And at night he even gets through sleep with two hands in his mouth and sucks, eats well during the day and at night. ? I hope this is normal? What can we give or apply if they start getting teeth?