I've tried everything! But I still can't seem to gain weight!?

I'm 16, and I have been trying for years to gain weight. I have always been skinny and I feel really self concious about it. Physically my body doesn't look that bad, I am quite toned and I have quite a broad frame, however I am only about 130 lbs. I eat healthily, I have tried to eat foods high in carbohydrates. I have even tried weight lifting but thats difficult for me because I have a problem with my left hand which means I cant lift with it. I was hoping that when I hit puberty I would fill out and put on weight, for some reason I haven't and all my friends have. What can I do? I get really down about it :(