Yours is at the age where they start losing teeth...A lot of times you won't find any teeth laying around, they usually end up swallowing them .....
It's not unusual for them to have a few that don't fall out at all so you have to keep a watch on that because if the adult teeth start coming in and they still have retained baby teeth it may throw off the bite of the incoming teeth....
Usually the retained teeth will be extracted when the pup is spayed or neutered so they only have to be put under anesthesia once....I hope this was helpful....