What type of device are you using for your measurment? Aneroid, electronic, or mercurial?
I am in a similar situation, but I am only 15. I was at 146/93 (average) when I decided to not run on a daily basis, or run at all for the months of April to June. Even after exercise, it was still high (136/87). I would try a better diet (low sodium) and if they are still fairly high, get a measurement done by a doctor or yourself with a mercury sphyg. I am only saying this because electronic monitors, even when properly calibrated, can be off by more than 8mmHg. Mercury never fails, and is the most accurate that you can ever get.