Corn snake feeding

[Ree]

Hi everyone!

I am new to snake world and recently I adopted snake from friend that was unable to care for it anymore. To my knowledge, it's morph of corn snake. She (?) is about three years old and 55 inches.

I've done my research, but I am still unsure about feeding. Previously she's been fed tree mice once every three weeks. Is it enough for snake that size and age? I would like to be able to still handle her regularly without her pooping on me. And also is she on healthy weight?

Little additional question, would anybody here be able to tell me if it's male or female?

Thanks!