Late bloomer

It seems that Im so behind in hitting puberty. My boobs are still an A and im 16. I see sophomores with two sizes bigger than me. I'm also only 5"4 and I just feel like I'm not going to grow anymore. The only hope i have is that my boobs are very tender. I know I'm not pregnant and I hope it's nothing worse but for the moment im hoping it means my boobs are
Growing. Why is it that im so late?