Each of the titans is a piece of the original Ymir's completed titan, so it's safe to say that each of the current nine represents not only one of her powers (Reiner's is her titan's armour, Pieck's is her titan's endurance, Armin's is her titan's size/desctructive potential, Zeke's is her titan's connection to other creatures or something, etc) but also a certain aspect of her being. I'd say that the Female Titan is just the part of her power that allowed her titan form to appear feminine instead of how titans normally look, and I'd probably guess that anyone who had it would manifest a "female" titan, despite their actual human gender (After all, cadet Ymir's titan, Willy's sister's titan, and Pieck's titan are all masculine/genderless/normal despite their shifters being all female, so the same isn't too far-fetched happening the other way around). The only thing I can think of that disagrees with this one would be Frieda's titan being female as well, though that could probably just be attributed to either her royal blood or the Coordinate (or both) making her titan look more "dignified" or "royal" or whatnot (Eren's titan seems to look more human than most as well, with the Coordinate's influence).