That sounds fine! A genderfluid character who's presenting as and being recognized as female imo definitely qualifies to be included here, so go for it. :)

And no, there's no maximum amount of fills, so just divide things up however's practical for you. As long as you're not posting a vast amount individually, then it's absolutely okay to split them up enough to manageable. (Also, fifty four and more to come? Wow, hats off to you, because that is very impressive!)