Is this normal? what about you?

Hi, I'm 18 and I have 18 and 1/4 inch biceps and curls 50pd dumbbells. As far as people saying your small, its not a big deal. Some people are naturally bigger than others and you can always work on it never mind the fact I have met guys your size with that can curl about the same that I do. It's all in the training and smaller guys can be just as strong but need to work twice as hard for it. good luck man