What are you looking for in the blood test? It doesn't sound like you are pregnant, otherwise the tests would have returned positive - but there may also be other conditions to be concerned about.
That's why I would suggest speaking to a doctor.
You'll be surprised how many women have irregular periods, so you are certainly not alone - but I know from experience that your mind won't be at rest until you hear from a doctor that everything is ok.
Until then you will always be worried about the "what if"...
