Blood Work Shows Estradiol Level At Less Than 5. I

Blood work shows Estradiol level at less than 5. I am a 51 year old female somewhere in the menopausal state. Is this something to be concerned about? (My physician said no) Could this be the reason I have gained quite a bit of wait with no eating or exercise changes? Could this be the reason for very, very low sex drive that was quite health last year? Thank you - Shelly