Track..???............?

Okay soo i have heard that the average girl speed for a 100m dash is 12-13 sec. but i dont think thats right. I have raced alot of girls and their times were around 15 and plus sec. The fastest girl i know runs hers in 13.8 sec. .. Anyway. My fastest time for a 100 meter is 14.54 but im 14 years old and 4"11 so is that good or bad? And is there anyway i can increase my speed because i want to be as fast as possible. Oh and btw i am going to be a freshman this year :)