My Beard Only Grows under my Chin and Jawline

So, I am 28 years old, don't drink or smoke or anything close to it, if that means anything.

I have had my beard for about 4-6 years now, and it has only ever grown under my chin and jawline, I suppose being the 'Neckbeard', if you like. It doesn't look HORRIBLE, it is just not what I want right now. I grow it out a little bit to hide the mild patchy-ness of it, and my hair is long right now, going about to my shoulder.

I wondered if there was a way to help it grow normally, like around my jawline and cheeks and such? I've tried rapid shaving it, which I heard should force growth, but it came to nothing. Is there anything I can do to make it grow normally?

Thank you for your time, in advanced.