Can I demand a blood test

I’m 5 days late I had a faint line on on a 10mUI and a negative on 25mUI. I’ve had that period feeling past 8 days and not come on. I know the doctors tests are not as sensitive. Could I demand a blood test?

I’m worried about Ovarian cancer etc (it’s in my family)

Also has anyone missed a period for negatives and then a positive?