The answer is yes, you can be a model even if you're short but the problem is it is very difficult to be a runway model.
Modeling like every job has specifications that every model would have before you can be considered and I think one of the criteria for being a runway model is that you'd have to be tall or at least 5ft 9 inches.
The good news is that modeling is not only about the runway, in short they have so many different types of modeling e.g face modeling, hand modeling etc. And these models make just as much money as the runway models, so if it's the money you're after you won't be at a loss.
I hope I have been able to answer your question.