What can i do so that i can at least make a reasonable attempt at being an NBA player?
My grades are good, Im only 14, 15 in a month or so. i shoot very well mid-range, i'm 5'7 point guard. Just not very fast. Have fantastic stamina.
Getting into the NBA is like getting admission to Harvard or Yale. When there are tons of highly skilled people trying to get into a single organization there is going to be a huge luck factor involved that you will have very little control over. That's neither fair nor inspirational but it is the reality that simply must be faced. I am certainly no professional athlete but I would think that the best thing you could do for yourself would be to keep working on and improving your basketball skills (obviously) and also keep your grades up and academic work strong so you can get into the best college with the best basketball program that you can. College level basketball will be your best calling card into the NBA. So get involved with the best program you can and give it everything. As an outsider looking in, I would think that is your best bet to maximize your chances at professional basketball. And while at college continue to keep up your academic work in case playing for the NBA doesn't become a reality (and let's face it, there are plenty of talented players that never get that chance for a variety of reasons). At least with a good college degree there are other sports possibilities open to you as a career alternative (assistant coaching, team management, physical and nutritional training and rehabilitation, etc.). Also remember that there are other countries with professional basketball leagues (many European countries, for example) and starting out in one of these leagues might get you a chance at the NBA. So keep your options open because you never quite know where life will take you!
I'm afraid there's not a whole lot of call in the NBA for 5'7" people who are not very fast. Of course, you are only 15 so there is still hope for growth.
It sounds like you are not going to be really tall, though, so your only hope would be as a guard. That means that you are going to have to be as quick as you possibly can be and you are going to have to extend the range on your shot. Of course, the best way to do those things is to get stronger and to practice incessantly.
For quickness, you might want to find some cone drills and agility drills. Those kinds of drills will improve your quickness if you keep at them. For shooting, of course, it's just shoot, shoot, shoot. Set yourself a goal for some large number of shots each day this summer. Make sure you use good form, especially as you get tired.
You may not make the NBA, but improving your game will be a good thing no matter what, because it will be satisfying to you to see yourself rewarded for hard work.