If a girl finds being called a girl insulting I don't want them as a partner.
I truly hope you don't mind being called a "boy" in that case.
The correct term for someone of the female gender is as far as I know still initially a "woman" (also not a "female" as you use in the topic. Would you also ask for a "male"?). If you want to be more flattering, you could say "young woman". Some women don't mind being called a girl (hey, it does make them sound younger than they are, generally considered a good thing), and when under a certain age, it's definitely the correct term (as is boy for men).
Girl, although sometimes assumed to be the female equivalent of "guy", is actually more condescending. (In linguistic terms, the lesser used "gal" would be the technical equivalent I believe.) Also, the proper or improper use of the word may depend on the relation you have with the recipient. Calling a woman you don't know a girl may be frowned upon in general, and is inappropriate in a formal or professional environment.
"A female" on the other hand refers to a more abstract interpretation and is more generally used for animals (or other more abstract concepts that have a gender, e.g. a robot, a video game character, ...) than for humans afaik, so you may not be interesting in playing with that? Technically, when you ask for "a female", any man with a female WL character fits your description.
Maybe some native English speakers can give more detail, because I heard the interpretation and sensitivity of the words also depend on the region and associated dialect.
Also, finally, following Styxie's comment: a woman on WL may be more likely to behave in the way you don't want than a man. After all, these are women who (1) are used to move around in a male-oriented environment and (2) interested in a game that has connotations with war tactics and requires abstract thinking. I think most will be blunt enough and stand their ground just like the average man on this site, rather than being all cutesy as you think they may be.
