Hmm difficult question. Being a "typical" guy, i think it was when i was around 18. Sex drive went into overdrive! My mind kept wandering waaay too much, and in the most innapropriate places. Its calmed down a lot now though. Dont get me wrong, i still like a bit of *hows your father* but its more of a supplement now than a necessity.
I'm similar to you in the fact I am only sexually attracted to people I am in love with or are crushing on. To my gay friends, which there are many, I'm clearly known as the one who is a "tease", of all things. I speak freely about everything, and sex isn't something I cover with a rug. Despite my fluency in the sexual language, and my involvement with my friends who are mostly sexually active, I'm the one guy that doesn't really partake in the action. Why is that? I honestly have no idea, and I have always been like that. It's not a bad thing that you are not and were not very inclined to sex as a teenager, and it's perfectly normal coming from my perspective. I've always looked at as this: I'm not a very sexual person--I make due with my life without it. You are not alone my friend.
So far for me, it's the early twenties, though I've heard many women's levels of sexual attraction peak in the late twenties and early thirties...I guess I'll see when I get there...
For me, my sex drive was almost uncontrollable in my teens, at least compared to now. I probably wouldn't have told you that then, though, 'cause I didn't have now to compare it to. Back then, I wanked twice or more a day if I didn't get sex. Now it's maybe twice a week. I'm also now on meds for clinical depression, ADHD, and tachycardia (rapid heart rate), and all three of 'em have libido-killing as a side effect. Still, though, my sex drive was starting to chill out before then.
so far right now is when I have been my horniest but if I look back then I have basically always been as horny as I am now without any major changes.
thats how i feel... but if you count random erection though out the day...like ever since i was 15ish - present...but that could be the lack of relationship and intimacy... but who knows...
every year since puberty get hornier and hornier not sure when it will peak but cant imagine being any hornier
I have to say when i was 14-15, right now I'm eh with everything. I seriously had dirty thoughts in class when i was that age. Like I picture me having *eh hem* with certain people in class.
