I Have Had A Inter-vaginal And Regular Ultrasound Done. My

I have had a inter-vaginal and regular ultrasound done. My ovaries were normal and the pelvic area was unremarkable. They found I have a thickening of the endometrial lining of 1.3 CM. My doctor has recommended a biopsy. I am 45 and had early onset of puberty. I have had one period that lasted for over 3 weeks, should I be concerned?