Sara Jane,
I lived in Miami for 20 years, and, sadly, you are probably going to have to mail order everything, try it on, and return what does not work. South Florida is all about water sports, not walking. Hook up with the South Florida APOC chapter (very active) and they might help.
As for packs, first, thing, go online and learn how to measure your torso length. Don't guess by height. I'm a foot taller than my wife (see picture), but our torso lengths are very similar (I'm all legs, she isn't). Then try to order packs that might fit.
My hobbit-sized wife (5', 110lbs) ended up carrying an Osprey Stratos 24L (that I originally ordered for me). Stratos are "men's" packs, but for her body type (very athletic, not much curves), "men's" packs work better. I went with the Stratos 26L because I prefer the drawstring top to the zipper closures on the 24L (easier to pack; no worries about blowing out a zipper).
Buen Camino.