I have a red eared slider turtle that i got from China Town New York 3 years ago he has not been growing he is still the size of my fist is that a bad thing cause in the pet stores there bigger

Well, I don't know how much you know about turtles. I'm a breeder of box turtles, but I have quite a few of red eared sliders also. Here's some importrant points...
-Turtles need SUN to digest and grow properly
-Turtles nedd lots of space to grow
-Turtles need to be fed a couple times a week

It's common for owners to think that their turtle isn't growing when it actually is, it's just that they're around it so much it doesn't appear to be growing any larger. Another growing problem occurs when the turtle is kept in limited space, therfore, doesn't feel comfortable which results in the turtle not eating and etc.Or maybe, the size of your fist is as big as your turtle is going to get. Hope you find your problem!