Is it possible for my cat to only have one kitten?

It's possible, especially if she is a young or small cat, or if she didn't get adequate nutrition during the pregnancy. It's not common, though. Does she still seem pregnant? It's possible for a cat to have delayed labor, if she was bred far enough apart. It's also possible for things to go wrong in the labor, and for a kitten to get stuck in the birth canal and prevent the others from being born.

I have no clue, but my cat had one kitten last night or today, the cord is still attached but the kitten is eating well, and I have no clue if there is more or supposed to be more, or if she is supposed to only have one, she is very affectionate and is eating and drinking and going back to her baby, so I am assuming that there is no more kittens, and also she only has one nipple really big, which is the one the kitten is using... have no clue what is normal, if one is or not...

My cat only had one kitten, too.
She is very small and we expected this of her.
I would not worry. Try to leave them alone. And if the mother is abandoning her (not feeding, not cleaning, not sleeping with, etc.) I would begin to worry. Try getting baby formula and feed the kitten yourself.
There's a difference between the kitten not feeding and the mother not feeding the kitten.

If the kitten does not try to suckle, there is a very good chance it will not live, bring it to the vet immediantly.
If the mother just will not feed the kitten, you will have to feed it yourself. Once you begin to feed it yourself the kitten ill rely on you for everything. Bring it to a vet for a checkup and ask the vet for any advice.

My cat delivered 3 weeks ago today. This is her second litter, she had on normal healthy baby and one was born stillborn, try as I might to stimulate breathing he just wouldn't. Her first litter she had 5 all healthy kittens, so I'm not sure why this time she only had one. But after 3 weeks the kitten is doing great. My only concern is of the father that lives in the house as well. I have caught him twice now by the kitten while mother is eating or drinking, and it seemed he was trying to bite the kitten. Is he just trying to play or seriously harm the kitten? I tried separating them but he just won't stop crying until I open the door for him to be by the mom and kitten. Any suggestions?