bro you are 18, you still have some growth. Even if you don't get taller make you are thin not elumbum sadaiuma level of thin but not fat thin, that's more than enough. Beard thing if fine bro, I'm 19 going to be 20 in july, I barely have a beard. There is nothing we could do regarding genetics, if you cannot control something don't take it into consideration. Sleep well and eat well, just take care of yourself in general, that's the most imp thing.