Well look at different brands, try them and if there's nothing you like then get custom. Its important that your boots are comfortable. And also mountain horse tall boots are really good so try those too.
Try Mountain horse i am 5'1 had the same problem ended up with mountain horse Venezia they have a large range of boots with different sizings mine took awhile to break in but are great now
I'd look and try on some pairs at a tack store, but you might need to go semi custom.
Try Veredus. Otherwise fully custom boots are the choice
I got a semi custom pair, im 4'11 full grown and have big feet and short legs, I haven't found anything off the shelf that fit! I did the semi custom Tucci boots but Deniro has alot of semi custom boots! Semi custom is better if you dont want to pay for complete custom.