Welcome to HCM.
Do you have sparse hair growth in the arm pits and pubic region also?
If yes then you have hormonal
problem. You have to consult an endocrinologist
and get the hormone tests done and if required hormone replacement therapy
has to be started.
If hair growth in other parts of body is adequate, then you do not have to worry. In due time beard will grow in all it's glory.
Wish you all the best.