Do you chart your fertility? Do you know if you even ovulated? All women go through cycles where they don't ovulate and so (obviously) don't have a period. Stress is a big factor in ovulation, but even if you aren't stressed, you are bound to go through cycles of annovulation. It will happen more and more as your fertility decreases and you approach perimenopause and menopause. I think all women need to learn to track their fertility so they don't have all these worries. Ever since I started charting, I've never questioned whether or not I was pregnant, you know on paper before most pregnancy tests or symptoms can tell you.
You don't need a blood test, a pee test is accurate enough.
I saw one of the earlier posts. It's a falacy to think that if you have a period you have ovulated. So if women are having fertility issues, assuming that they ovulate just because they have regular periods is a bad assumption. A good OB should have known this:(