What should I do about my beard, which has become unkempt after trimming it, knowing that my parents insist that I trim it just once so that it grows out evenly? And is hair growing on the neck considered part of the beard? And what are the boundaries of the mustache?

"Letting the beard grow is obligatory, and shaving it is prohibited, according to the preponderant opinion of scholars. It is permissible to trim a small amount from its sides to make it uniform in length. Scholars have differed regarding the definition of the beard. Some believe it is what grows on the jawbone and chin (the two jaws), and they permit trimming the hair of the cheek and what is adjacent to the neck. Others believe that the beard includes what grows on the cheeks and what follows it on the neck, and it is not permissible to trim anything from it. The mustache is the hair that grows on the upper lip."