If you can see them then I probably wouldn't worry - they will come through eventually! Like AJP said the dentist will probably do an x-ray if you are concerned but there is probably no point if you can see them?

My DD seems to have less teeth than all the other toddlers I know at her age (she has 6 at 14.5months) but turns out DH was a late teether...........so maybe a genetic factor for you guys too!