Thanks for writing and the tag!
Very, very good point. As MeanOwl says, futozao can be reasonably comfortable with smaller hands. However, if you also have a petite stature as well, I think it might the overall size and weight of futozao shamisen a bit less manageable than it could otherwise be.
Before starting Bachido, I had a very petite friend who got pressured into starting with futozao, because our mutual friend gave off a strong but ignorant “tsugaru is the only real shamisen style” whenever they got together. Needless to say, she eventually bought a full size futozao shamisen, and while she could hold it, it was just uncomfortably big and she ended up stopping a short time later. In hindsight, I think a hosozao shamisen (which neither of us had at the time) would have fit her like a glove and would’ve made the experience much more fun.
In short (too late), I think you might find the Beginner’s Shamisen much easier as your first shamisen, and perfect size for playing in general. Tsugaru pieces can also be played on it as well.
A quick fun fact! In the next few months we’ll be releasing a chuzao minyo-style Raven! It’s currently in my studio ready to take promo pictures, but I’ve been swamped in the workshop. Anywho, soon there will be super sexy shamisen options for the slender styles!
Re: bachi size. Given what you’ve said, I think the Small size should be perfect.