Hello, everybody

I have a following question. I am 22 years old. When my blood pressure was first measured in my life (half a year ago) sistolic one was 130 on the left arm and 140 on the right arm (I was anxious because I was having a medical test).
Then I went to the chemist and asked them to measure my blood pressure again (I was a bit worried again). The results were quite the same.
Being in Australia, I went to GP and told him about the problem. First the sistolic pressure on the right arm was 150 but I had been very nervous because of the visit to doctor. He suggested to try it again and in a minute it was already 140, and by the fifth time it dropped down to 135. The doctor supposed it was caused by anxiety and said I could buy a blood pressure measuring machine myself so that I can monitor it in normal conditions to make sure there are no problems.
When I returned to my home country I went to chemist and asked them to measure my pressure again. I tried not to worry and as I felt I was not worried but my pressure was again 150/90 on the left arm .
I am going to buy the machine but maybe you can tell me, to your mind can such a situation be normal and caused just by anxiety or does it more than likely mean an decease?

Thank you a lot!
P.S. I am taking Marvelon. Before I started taking it the pressure had been around 130-140, now it shows sometimes 150 as I described (sistolic).