I had the same thing happen to me. I basically stopped growing in height by 8th grade (5'9") so for that age I was fine playing down low, especially since my jumping ability has always been impressive. When I got to high school I played forward on the freshman team, but the coach told me that if I didn't grow in the summer I would have to adjust to playing guard because I wouldn't be able to get away with playing forward on Varsity or even JV.
I never handled the ball on the perimeter when I played as a forward, and I only shot 5 threes all season (made 2). So in the summer I worked really hard on my shooting and my ball handling since those were my obvious weaknesses. I never did end up handling the ball a lot in the coming years, but I did shoot a lot of 3's . I actually led the Houston area in % for a good part of my junior season.
So I guess my advice to you is work hard on developing an outside shot. That's probably going to be the easiest way to make an impact. You have to work on the ball handling too, but there's no reason you have to develop awesome handles unless you're planning to run point guard. Just make sure you can put the ball on the floor for a couple of dribbles without losing it and you should be ok.