Greetings. Do not worry, reduced hair n the moustache and beard may be a constitutional feature; this may be related to hereditary delayed growth of facial hair - in case your father or elder brother had similar issues. Since you have normal armpit and pubic hair - the possibility of hormonal deficiency is not likely. You could try using hair peptide lotions - however, the efficacy of the same for growth of facial hair is not guaranteed. IF you are really desparate for facial hair then hair transplantation may be the ultimate option.

This is limited details and more precise information is needed about your skin condition which can help in planning a treatment. A thorough history, clinical examination and appropriate laboratory tests will be needed to solve the mystery. A photograph would have been helpful. Consider seeing a Dermatologist for proper diagnosis and treatment plan.