I am 54 years old, and my period is 6 days late. how likely is it that i am pregnant? or is there something else that could be causing this?

Menopausal changes: The average age of menopause is 51. In our 50's there is greater variability in our cycles (if a woman has cycles) due to hormonal fluctuations. The chances of pregnancy are nearly zero, though not quite. Def of menopause is 1 year w/o a period. Likely your late cycle is due to decreases in hormone production from your ovary. See a doctor if it concerns you, or wait a bit more.