How do I know if I have gone through Menopause?

I am 48 years old and have never missed a period untiul I was 15 and pregnant. Only pregnant once. I have never been more than 5 days early or 5 days late. My periods were 7 days until after my daughter was born. They went to 5 days. Whan I was 32 years old, they went to 2 1/2 days. That was the case for many years. Now I have had my peroids for the past 3 years for 4 to 6 days. The past year I have had them for 4 1/2 to 5 days. Some months heavy and some just normal. But 2 years ago, I had a medical exam, found 5 lumps, found out they were caffine. I was told that since I was premenopausal, I need to take care to not intake so much caffine. I have had a menopause blood test 2 years ago I think, but it was normal, no sign of menopause. Now I have missed my period last month and I have had all the symptoms of my period, I get sick to my stomach, my breast are sore, I am moody, I am over tired, I get bloated, I sleep alot, have the "don't cares". What could be the reason? could it be cancer or menopause?