...  I thought I had the adult cats both fixed, but

Well, jhill,
Assuming that you really are simply clueless and not a troll, I think you
should do the following:
1. Take the kittens to the vet who supposedly spayed or neutered your cats.
2. Leave the kittens, and ask for your money back.
3. Then take the adult cats and the money you get back from the first vet to
another vet and have it done right.
Annie