There really isn't petite specific cycling gear. But, there are companies that make large varieties of x small sized jerseys/shorts that I buy from.I mostly buy from Terry, but Sugoi, Shebeest, and Sheila Moon all have xsmall sizes. They are not cheap, though. You can find some good stuff in the sale area of TE and Terry web sites. You can buy shorter shorts, too, although I tend to wear 6-7" inseam ones because I like the feel of them.
There are petite sized non-cycling tights that can be worn over your shorts.
I am 5' 1" and I have plenty of choice (too much, actually).