you know, it could just be heredity. Many men do not have thick hair growth on their faces....what about other men in your family? do they have heavy beards? are you blonde? blondes frequently have light beards...?
Most dudes at that age cant grow thick facial hair. Most of the guys I know are in mid to late 30's and just now having to shave every day and able to grow full facial hair. Genetics has a lot to do with it also.
My husband has thick stubble too but he has never been able to grow a full beard either. Once it starts to grow in the hair seems to have tiny bald spots so to speak. It's probably just they way your hair grows in.
Besides most women like a clean shave or a slightly darkened stubble, so be happy!