Welcome to HCM,
it seems that your body structure is like that since before or you might be under weight or mal nourished.
take plenty of protein,fat and carbohydrate
in your diet.
Take some multivitamin
You have not mentioned your sex history,growth of your sex organs,growing of hairs on various parts of body,sex likng etc.
if there is problem about this then you may go for male hormone estimation.
Ok and bye.