so, i spent the summer riding my childhood bike for exercise, a toys-r-us mountain bike which my brother broke all the gears on a decade ago and no brakes. i really enjoyed riding, but the bike was a nightmare. now, with the help of some amex reward points, i'm finally getting my first 'real' bike. and here is my dilemma:

how to fit a bike that I won't get to try?
also, my proportions are a bit wonky.

i was planning to get the trek fx 7.5, pretty spendy for me, so i want to be sure it fits right. it comes in a regular or WSD frame, but here's where it gets complicated...

i'm tallish, 5'8", and 50% of my height is in my legs; that's 34 inches. (average is 45% among women). to make the matter weirder, my arm span is two inches larger than my height (longer arms are typically a male trait). size charts which go by height put me on a 17 to 19 inch bike; charts which go by inseam put me on a 21 to 23 inch bike (that seems really wrong, that would be the same as my 6'4" brother)

So if i was only leggy, i would go for the largest WSD, 19", with a stand over height of 30.2 in (seems reasonable). but i'm worried that my orangutan arms would make the WSD feel cramped. or would my short torso make up for that? the 20" men's frame has a stand over height of 30.8 (also reasonable), but would I feel too stretched on that frame? though I could technically get my leg over the 22" men's, i'm sure that's too big. maybe women should be fitted for men's bikes with a tube sock stuffed down their pants. lol.

long story short, would the 19" WSD fit the best?