male skeletal maturity

I am 18 years old and my shoulders are not developed like a man's (still somewhat thin shoulders, not rounded, thin, and angular), although I have already started shaving, though I still have a little acne. in the past 8-12 months i have been getting very little sun (vitamin D) and very little calcium. would this hinder my skeletal growth, and cause my shoulders not to fully develop if puberty ends before my shoulders fully develop? or will my shoulders eventually fully develop regardless of how long it takes? Secondly...if i used to carry a heavy trumpet case around usually with my right arm during school in my earlier adolescent years, is that the cause of my shoulders to become uneven, as in when i relax, one side is a little lower, and also shorter & differently shaped than the other side?..and would my shoulders eventually even out with time and skeletal maturation? Thirdly, are my shoulder's growth plates most likely fused already?(meaning no more growth is possible), or not yet?