Hi - no question is stupid! Blood tests can't definitively so whether you are post-menopausal because they vary so much because even when peri FSH levels sometimes go into the post-menopausal range. However as Annie0710 says, a blood test which showed raised FSH and also combined with age and symptoms would give you an indication that you are going through menopause, as you don't have a menstrual cycle to tell you. Sometimes hysterectomy causes ovaries to fail earlier than they would normally - so I understand.
Hurdity x