Bet you've got a male - that sounds like classic mating season behavior to me. There are several methods of sexing snakes:
1) visually, there are differences in tail structure between males and females. If you can get a good pic of the underside of the tail from vent to tip and post it in the breeding forum, I bet you could get some opinions
2) probing, which gives me the creeping horrors and I feel is best done by a pro, uses a rounded metal probe slid into the snake's vent. If it goes in deeply, it's in the hemipene of a male, if it stops quickly you've got a girl.
3) popping, which is only good for hatchlings, so not a method for this snake
4) behavior - since you have a known female (if you are totally sure, that is) you can put them together and see if the possible male tries to mate with the known female. Wouldn't leave them together too long, as your female is too young to be breeding yet.
Honestly, I think I'd go with 1 or 2 if I were you. Some pet stores and/or vets will sex your snake with a probe for a reasonable price (usually around $5), but I bet the folks on here could tell you with reasonable certainty for free if you get a good photo.