Last year, we took in a pregnant stray. She had four babies on July 2nd, and we were able to rehome two of the kittens and the momma (who is now fixed, yay!).
We have two of them: the second oldest, who we call Smee, and the runt, who we call...Runty. Yep. They both seem to have the same dad (we're pretty sure we know who both dads were...we had three orange kittens and one black, and two males of those colors were wandering around before we were able to rehome the mom).
Smee has grown fine. The day he started spraying, we scheduled an appointment with the vet, and as of now, he's what anyone would call a normal cat. He'll be a year old in about 2 1/2 weeks, and weighs the normal amount for his age.
Runty, on the other hand, has not. She started off as the one maturing the fastest (first to open her eyes, first to walk...her tiny size probably helped), but quickly stopped. She's still tiny (about 5-6 pounds tops). Looking at her from her backside, she has the normal girl parts, but has never gone into heat, has no teats, and hasn't had any changes in weight in at least 3 months. Being so close to a year old, this seems really strange. She acts absolutely fine. Still crazy like a normal kitten, but underdeveloped physically.
Is this reason alone to take her to the vet? I'm the third of three kids going in college, so we don't want to take her in unless it's absolutely necessary. It just seems so odd that she stopped growing.