Yes, she is likely mature. This species has a reputation of eating males and being difficult to pair successfully. My two females are both 5.5" full grown. Were you planning on breeding her immediately? Make sure she is well fed. Good luck!
@Cyaneo A lot of people in Canada seem to get males. I'm sure that one will come available for you. Even an immature male is good, since they take so little time to mature compared to some other species.