My wife is 4’11” and has a 27″ inside leg. She rides a XS Specialized Vita and a 12.5″ GT MTB. I think it is possible you need to check that inside leg measurement again to be sure. Anyway I would recommend Specialized for very small bikes for women as they are the only company that does them well at a reasonable price AND imports them into the UK! I did look at a Scott for my wife and a couple of other brands but the UK importers said they didn’t bring the very small ones over.
As far as “traditional” bikes go, I think you will struggle. Things like Pashleys sell in very small numbers compared to the big companies and it may not be worth them making very small sizes unless it’s kids stuff.
Good luck anyway.