Well I cant say much, but you might be a late bloomer! A lot ot guys that today are like 30-40+ with big and dense beards had even less than what you got so dont lose hope yet!
Some guys use something called "minoxidil" to promote hair-beard growth, but as you are young I do NOT recommend it, just give it time. But if by the time you are 40 and still havent got a beard then its something you can consider but not now.