How To Diagnose To Confirm Presence Of Microcephaly?

I am a 48 year old man, 6, 2 tall and living a normal life. I am not very academic and work manually for a living. My head has always been too small for my body and now that I am getting older and middle age spread is happening the effect makes me look worse. Is this microcephaly ? I have always felt very consious about how I look and I feel the problem is getting worse as I get older. Do people with conditions like mine suffer any other health issues ? I have considerd dieting in the hope my boby would stay skinny making my head look more of a normal size and I have wonderd if I put on weight would my face fill out making my head look bigger ?