I'm 5ft9, my mare is 14.1hands, and I look fine on her. My legs are a smidge too long for her but it's really nothing bad. She is, however, the widest, roundest horse in probably the entire universe. Hahaha But seriously, she's super wide (she's a Polish Arabian).
Like the previous posters said, it all depends on the horse's (pony's) depth of girth. A very narrow 14hh pony would make you look too tall but you'd probably look perfect on a rounder, wider pony of the same height.
It also depends on your weight to some extent. If you're a larger person, you probably want to look more into larger horses just so you don't have to worry about overburdening the horse/pony but an average sized person of your height should be fine on a pony. Personally I wouldn't go any shorter than 13.2-3hh (unless the pony is ridiculously wide) but I would for sure think that round/wide ponies in the 14hh range would suit you well.
Another thing to keep in mind is that many taller pony breeds experience height crop-outs over the 14.2 pony height cut off. So, for instance, you could find a 15hh POA [Pony of the Americas, my favorite pony breed of all time] which would have pony characteristics but be too tall to technically be a pony.
Fabio - 13 year old Arab/QH gelding
Hazel - 14 year old Angora goat
Atticus - 4 year old LaMancha/Alpine cross goat
Rest peacefully, Lacey.