
Same here, one of my girls had reached her 2nd birthday and no season, so off to the vets, full blood works done, everything came back clear. Two weeks later she came in season and it was a full blown season too, I guess she was just a late developer too.
My vet did say he wouldn't do anything until she reached 3 years old, because although uncommon, some bitches don't have their first until around 3 years of age (although I've never heard of it)