Probably best to ask the person in charge of your Confirmation prep. Confirmation names aren’t something we choose primarily because we like the name but rather because we like the saint.
I know at my parish, I’ve had females choose male saint Confirmation names and vice versa. I’ve also had some opt for different, unconventional spellings (though if I recall they were all simply spellings from another language, not something arbitrary). I don’t know that I’ve seen anyone try to feminize a masculine name or masculinize a feminine name. But if your pastor is okay with it, then go with what he allows.