I agree with your doctor, I don't think you're menopausal either (one year without a bleed). In peri the thickness of your lining is nothing to worry about, it can be 16mm if they scan just before a bleed. They sent me for one too because aged 60 I had 2 bleeds - they called them 'unexplained bleeding', I called them 'periods'. All was well. Don't worry, I think they've sent you as a belt and braces measure.