Dush -
It sounds like you may have borderline hypertension. Certainly a diastolic of 100 is too high, but your diastolic isn't consistently high. Same thing with the systolic (top number)...160 is high, 140 isn't too bad (although still slightly high for someone your age).
My suggestion would be to continue to monitor it for a while, and discuss this with your doctor.
Most people don't take hypertension seriously enough. Over the long term, it can put you at increased risk for heart attack, stroke, kidney failure, etc. Hypertension affects every single organ in the body. On the other hand, I certainly don't think your is so high that you need to panic. Discuss it with your doctor, and get his/her advice re how to monitor and how often, and at what point he would recommend medication.