Hi Beth
If you're flat footed you probably overpronate, but you should get your gait or footfall analysed to make sure.
As for shoes, well, that's very much a personal preference. I find Nike antipronation shoes to be very comfy cushioning-wise for my relatively light weight, but there are more makers and models and variations out there than you can shake a physio's bill at. You'll have to spend some time trying on as many shoes as you can find, plastic card in hand.
Dare I say it, but that comes naturally to females anyway. Good luck and happy hunting!