I have borderline high BP (it was around 130/90 before treatment, and even higher when I was on birth control - 140/95, or something like it - I had to come off the pill as a result). I was actually diagnosed with that first, and then PCOS. My mother and grandmother have high BP, so maybe it's unrelated, but I also suspect that they both have undiagnosed PCOS too! I think it probably is more likely with PCOS because it can affect all aspects of cardiovascular health. I don't think you should blame yourself. High BP can be at least partially genetic, and PCOS stacks the cards against you in many respects. I didn't think I ate a lot of salt either, but my doc was highly critical of my tofu/soy sauce consumption, and my occasional Marmite fix (I'm British by birth!). It's strange how much salt you consume without even thinking about it.
Right now, I take 120mg of Inderal daily for my BP, which is now normally around 115/80. My doc is much happier and the Inderal has also all but cleared up my migraines. However, I recently read that beta-blockers can make insulin resistance worse, so I think I'm going to go back to the doc and see if she can recommend something else for my BP. It will be difficult to give Inderal up and go back to having migraines!
I know that was a long answer, but I hope it helped