Might need to look for older bikes, like a Raleigh Colt or SpaceRider (24" wheels). My wife is short (she claims 5'-1" ) She rides a Raleigh Colt just fine. We were able to get a extremely short framed hybrid to fit her. IIRC it was a GT Slipstream. There are bikes out there, but you are 5% of the market so they don't make much to fit. FWIW I am 5% on the other end of the scale. Schwinn also made some decent bikes back in the 70's that were decent and could be had with 24" wheels.

Another option is to look at folding bikes, no I am not crazy, they can be easily adjusted to fit people from 4'-8" to 6'+. I would look at the ones with 20" wheels. Dahon is a reputable brand to start looking at. They work well for utility too if you chose the correct model.

Here is a picture of a couple of my vintage folding bikes to give you an idea of the size range. Mine is obviously the one with the looong seat post. But I can run it far enough down along with the handlebars so my bride can ride it just fine.

Aaron