Oy... you can bypass the post character limit by posting a few words then editing in the rest of your post (like I'm doing for this post). If you think "very long and involved posts with lots of research" aren't possible with this forum's format, you have yet to see the marvels that are Anonymoose's posts...
And again, there is absolutely no evidence in the lore to suggest that this occurs. In fact, aside from a few catlike features, the Miqo'te are very much more closely related to humans than any sort of cat. Just because their societal structure is built based off of that of lions (note I only mention this, as their biology actually doesn't point to lions specifically at all but rather just cats in general), doesn't mean every facet of their lives/the ways their bodies work are as well. (It's also stated in the Fat Cat minion's description that Miqo'te scholars actually strongly contest the idea that they may share ancestors with cats, even if their feline features, and other data from other researchers, suggest otherwise.) I mean, if you like the idea of a tribe of lesbian catgirls, more power to you. But it doesn't exist per the lore. Let alone the suggestion that female Seekers undergo chemical changes to more closely resemble males when a male is not present...
EDIT: Fat Cat's description:
Also adding in, the Miqo'te are no more feline than the Auri are lizards in that they only seem to share some traits of physical appearances. From what we know of their biology, they are mostly human, save for some facets of their appearances.Despite convincing research by top academics from around the realm and beyond, most Miqo'te scholars refuse to believe that there may be some ancestral connection between their race and cats (fat or not).
Also:
Pretty sure fan art has probably already done this. And then some. ;;;; No offense to the OP but this whole idea/"theory" kinda reminds me of some off-the-wall wild and crazy fanfiction I'd read on Tumblr or AO3 or something. (And trust me, there's some crazy shizz out there for this game.)