No sex drive until 17 years old iin

when i was a teen and everyone was developing facination with girls, i just didnt seem too intrested, i would look at porn magazines at the ages of 13, 14, 15 and 16 and not feel a lot, i wasnt attracted to men either, i had many oputunities to have sex but i just didnt want to, then at about 17 and a half my sex drive just kicked in like a switch in my body all of a sudden all i wanted to do was have sex, i would look aty pictures of girls all the time, i would persue girls just like my friends did a few years before, i lost it at 18 by the way, what im asking is is it normal for your sex drive to just kick in like a switch, it was literaly like one morning i woke up and that was it! i just have not came across anyone thats is the same as me.