Precocious puberty

My son is 9 years old. From the age of 6 he had sweaty smell in his armits and at 9 he has developed under arm hair  anda bit of pubic hair. i took him to a paedetric endocornolgist who then told me his penis is also very small. his height is ok. he went for some tests hormones and yet to get outcome.  my concern is at what age does penis of child start growing, as i would hate for him to have an abnormally small penis. is childhood penis an indication of how his penis will look when he is older. his father had no problems. Also this condition can it be reversed or are there hormone treatments.he was born under weight at 2.8kg and not sure my abuse of alcohol which i deeply regret then could be the cause. this was the same time the father left me.