Hi there ~
I understand your concerns. It is not uncommon to have less facial hair in certain individual past puberty. Although some men attain puberty later than the normal age group, if you have concerns with not have enough facial hair it might be right to first consult a dermatologist
as a condition called tinea barbae
may be the cause among others, and then to consult an endocrinologist
to check your hormone levels and have yourself examined. I hope this helped allay you anxiety
Take care and have a lovely day!