I can't really help with this, but you might be experiencing "autogynephilia". It basically means experiencing sexual pleasure from imagining yourself as or feeling female in sexual situations. It seems from a quick internet search that the opposite ("autoandrophilia" ie women imagining themselves as male in sexual situations) is somehow more socially acceptable but maybe that was just a few bad sites popping up.

In any case, if there is a label, then it means you aren't alone. If you aren't alone, then it might be possible to find people like you to help you understand, or console you or advise you...