I demoed a 15.5 WSD EX8 last year, and last year the men's and women's geometry was identical – it was only the colour and contact points that differed. So it'd definitely be worth checking out if that's the same case this year.
I'm also 5'4" (though have slightly longer legs and shorter body than you). I definitely wouldn't have gone for anything bigger than the 15.5" in fact, had a gone for the EX8 (I opted for a men's 14" Orange Five in the end) I may have gone for the 14.5" as I like small chuckable frames, and the 15.5" was on the longer side for me. I definitely wouldn't have contemplated going for the 16.5" though.
I'd definitely recommend trying one like you said, but based on my experience and your measurements, I reckon the 15.5 (from last year at least) would be about spot on.
Hope that helps?!