Alright...so first of all, within everything you wrote, I only found ONE question, and here's my answer to it: You're NOT doing anything wrong. There's nothing wrong with you not having had a boyfriend yet at the age of 17. I'll tell you what, when I was in the 12th grade, most of my friends were already 18, and a high percentage of them had never had a boyfriend or girlfriend, and there was certainly nothing wrong with them. They were intelligent, intellectually sharp, had many goals and aspirations and were well focused in life, athletic, socially outgoing, a visually appealing physical appearance, and all other good qualities that you could imagine, but nonetheless they had remained single all through high school and to the day when graduation took place at the end of senior year.
The fact that they hadn't been in a relationship up to that point didn't mean that no one of the opposite gender was not attracted to them, it just simply meant that the chance for an attraction to form and evolve into a relationship had just not happened (and a lot of times, this just happens by chance...you know, when just randomly, a guy and a girl who later on end up becoming attracted to each other, happen to somehow end up in a class together and seated close to each other b/c their lastnames are close to each other in the alphabet...or...his locker just happens to be close to hers, and they start talking to each a lot as a result of being physically located a few feet from each other so often).
Now, as for the rest of what you wrote, here's my response: My friends, whom I was talking about, who, up to high school graduation day had never been in a relationship, DID start relationships within their first two years of college, and some of them were very good relationships that ended up lasting a long time. A few of them are still together with that person after so many years. And for others, well, the relationship didn't go that well, BUT later on, they established other relationships. Finding someone to start a relationship is not something that anyone should be TRYING TO do...this is something that is supposed to come naturally, when a guy and girl who meet each other start to find out that they are attracted to each other. And after that, everything else is just supposed to come natural. Conversations between that guy and girl start getting longer, deeper, more meaningful, more valuable, etc., and then they start to either hang out often, or go out on actually dates, and then this gradually leads to a relationship, but it is something that should just happen naturally. And no one should be worried about this not happening to them by the age of 17 or 18.
A lot of your friends may be dating someone, but don't be too quick to think that you should, in any way, be jealous of them. To start with, the fact that those relationships exist does not mean that they're actually getting anywhere, or that they are really that meaningful and that deep. Typically in high school, there are a lot of little cute couples that are going on a very superficial relationship. They say "I love you, babe" all the time, but they don't actually mean that, they just think they do. One day, a relationship will exist between them, and the next day, it won't, because that's how lose that relationship is. A small percentage of high school relationships are actually solid and truly meaningful. There's nothing to be jealous of with regard to all the rest of them.
And also, I must point out that, based on what you wrote, it seems that you have a lot of good qualities. You're intelligent, you're social, you have an appealing personality, and you're pretty. So if you're thinking that there is something wrong with you, think again. There's nothing wrong with you. And there's nothing that you should be doing differently.
I don't want to make this too long, b/c I don't want you to spend too much time reading this, but I will say this too: Don't be shy. Just talk to a guy if you want. Take command of the conversation and look at him straight in the eyes, and tell him whatever you want to tell him. Be bold and don't hesitate to express yourself. Guys will have a lot of respect for your ability to be straightforward without being shy or hesitant.
I had a lot of friends who graduated from high school before having their first boyfriend or girlfriend, and they were awesome people.