My beard didn't fill in completely til I was probably 27 or so- until that point I would just play to the strengths of what I had, starting with a chinstrap then goatee then full beard once my cheek hair was fully there as stubble. I would keep it clean for a couple more years and take notice of what your stubble is doing before every shave. It's gonna happen for you just not right now and I'm telling you this as a brother that chicks appreciate it when you're clean shaven rather than walking around patchy, trust me