I was sexually active around the time of my ovulation. I've taken two pregnancy tests within the past two weeks but they showed up negative.Prior to that I had an extremely long period (a month long). I stopped menstruating for about a week and then started back (it seemed to be my regular cycle). I stopped and am now about two weeks late. Any info you can provide will be greatly appreciated

This could be early signs of menopause.
Some of the more common early signs of menopause, or premenopause symptoms and perimenopause symptoms, may include:

Changes in monthly cycle
Mood swings, irritability
Headaches
Hot flashes/flushes
Chronic fatigue
Depression
Aches and pains, cramps
Changes in body hair
Yeast Infections
Increase in PMS
Changes in sleep pattern
Loss of interest in love life
Water retention
Night sweats
Less vaginal lubrication
Fluctuations in blood sugar

Its best to see your doctor and talk about this, he/she can do blood work to see if you're starting menopause.