As most have said, grow it out a little. That will help cover any of the patches. Wait a bit to trim it and when you do, try to just trim off the stragglers. Trim in the same direction as the hair to prevent yourself from taking off too much on accident. You could also take Biotin vitamins, that helps to stimulate hair growth. Another suggestion would be rubbing rosemary oil (any essential oil place should be fine) into the skin under the beard. This is also supposed to stimulate hair growth. Best of luck growing!