Women, like men, come in all different shapes and sizes. IMHO, backpack fit is almost as individual as shoe fit, so a lot of trying on is necessary to find out what works for the individual. It's a really good idea to take along the stuff that will be carried in the pack, plus the weight/bulk equivalent of several days' food and water, to any try-on session--the pack has to fit the gear as well as the individual! The "woman specific" thing may be hype or may be true, depending on the particular woman. I have a woman specific day pack (with the "S" shaped straps) and a unisex backpacking pack (with relatively straight straps), and both are very comfortable for me.
My backpacking backpack is unisex but fits me just fine. The day it arrived, I loaded it up with my gear and "hiked" around the house for a couple of hours. Boring, yes, but I wanted to be sure it would work for me while I could still return it. From the very first try-on, it felt as though it had been custom-made just for me! It's a long-discontinued model (2005 Comet) from Six Moon Designs. If I were looking to replace it (I'm not), the first pack I'd look at is the Elemental Horizons Kalais.
I haven't been so lucky with day packs. I decided to ditch the one I had (TNF) because it weighs almost 3 lbs. and is too long in the torso for me. It appears that nearly all the manufacturers are going to "one size fits all" day packs which are far too big for my 15" torso and far too small for big and tall people. The few that are made for shorter torsos weigh 2.5 to 3.5 pounds, and I refuse to carry a daypack that weighs more than my backpacking pack (1 3/4 lb.)! I did find a nice lightweight summer daypack (on closeout--not made any more) that weighs just over a pound, but it's 19 liters which is too small for my winter gear. I'm still looking for a day pack for late fall/winter/early spring dayhikes that doesn't weigh more than 1.5 lbs., will fit a 15" torso, does have some structure to it, especially a good hip belt and fairly good weight transfer to the hip belt, and about 25-28 liters capacity. I'll consider one that is a little heavier if it has enough gewgaws I can whack off to get it down close to 1.5 lbs.