From what I could see from the stubble you've got, the coverage is almost perfect. You have the potential for a great full beard. Also, the thing you mentioned about the hairs growing out very straight, for now when it's short this is normal but if it's still straight once it gets some length that means your beard is growing straight. It makes it a lot easier for you since some hair doesn't grow on the opposite direction or to the side, if that's your case you're really blessed. There is really no reason for not letting it grow, do it.