How old am I?

Do you know? Because I can't seem to keep track of my own age. My birthday is coming up in just over a week. Somehow in the last few weeks or so, I convinced myself that I was 32, turning 33. I was on the phone with my 13 year old niece last night, and I said something about turning 33. She said, "You're 31." I said, "I am NOT. I am 32, I will be 33 on the 22nd." Again she said, "You're 31. You are turning 32. You were born in 1978. Do the math." So, sheepishly I did the math. I am 31. I am turning 32. Somewhere along the line, I just forgot. Aren't I too young for this? I feel like such a dork, especially since I had to be shown the light by a 13 year old who is now questioning my sanity.