A (retired) doctor writes..
Isolated measurements of blood pressure are not reliable, and are certainly not sufficient to advise initiation of treatment. The standard advice these days is to send the patient off with an automatic machine which takes the BP at intervals over period, usually 24 hours. The machine records the readings and the data are then uploaded to a PC where they can be printed out and displayed graphically.
I share your aversion to foreign chemicals in my body, but I should declare that I am taking blood pressure lowering drugs myself. I have no licence to practice any more but even if I did I would shrink from any but the most general advice, which is: 1. Relate the measurements of your BP to your own personal and family history; e.g. Did any of your first degree relatives (parents and siblings) suffer or die from cardiovascular illness, have you major risk factors for such disease, e.g. Lipid or sugar metabolic deficiencies.
2. If after careful assessment your doctor thinks you are hypertensive, try to get a realistic estimate of the risk of potential harm and loss of years of life in your case. This is not really more than an educated guess, but it should help to set your ideas in context.
3. If you are advised to take medication, again, ask for an estimate of the degree of benefit you are likely to gain, together with the potential harm it might inflict.
At your age you may feel that a risk of a year or so's life shortening or prolongation is insufficient to warrant the daily consumption of a pill which may have effects on your (ahem) amorous potential or similar. I would not pay much attention to rules of thumb such as age plus a random figure. More important is any evidence of damage to your heart and arterial system and consequent reduction in function of critical organs. Only your doctor can give advice in this.