Is Missed Period Sign Of Pregnancy Or Early Menopause?

I am 41 years old 5 6" and 9st 11lbs and I have just missed my first ever period (apart from when I was pregnant) now 42 days overdue, I have always been between 27-30 days without fail. I have done two pregnancy tests one was yesterday and one was last week and both clearly negative. I do not feel pregnant and up to a few days ago felt like I was going to get my monthly but nothing. I'm a healthy person, diet fine, exercise fine. I don't feel bloated however a bit hormonal at times (have always suffered with bad PMT) but apart from that nothing. Any ideas? Could it be the very early start of menopause. Back in 1999 I had cysts on my ovaries, however was still having periods regularly and the consultant was surprised I hadn't been in pain because they were big cysts, no problems since and no unusual pain apart from normal period pains (and even then they aren't that bad every month). Many thanks for your help.