Well dude... I'm heading into the same direction as you right now. I fell in love with the sport when I was 17. Now I'm 18 and going to be a senior soon. The question "is it too late" doesn't exist for sports in my opinion. It is never too late to fallow your dream. Never. For me right now, I'm practicing playing outside every single day in my front yard. I'm only 120 pounds, skinny, and your height. But... Does size matter in soccer? Not at all. Look at hulk!! He's buff and huge! And look at him again.. He is playing for Brazil... Look at messi... Only 5'7. He is considered short but look at him.. He plays like a master. If you want to reach that dream, you gotta work. A lot. You have to practice every single day nonstop and excersize and get in fit. But.. You are buff so that sounds good in my opinion.

I think you should join your high schools soccer summer camp if it isn't over yet. This will make you better and help you prepare for the team. And to answer your question you don't have to be the best player to get places as long as you have motivation and always give your best on the field.

just go training in the club you want to be, trust yourself and they won't miss a genius