Finally 12 weeks! AND the names are decided!

Amanda
Today I am finally 12 weeks exactly!  When do you ladies count the end of the 1st tritrimester? I've heard some say 12 weeks, some say 13 weeks, and some say 14 weeks. 
We also finally decided on our names! Owen Thomas for a boy (that one was decided when I was pregnant with my daughter last year), and Carolyn Claire for a girl! My grandma's name was Carol, and my husband's grandma's middle name is Carolyn, so we thought it was perfect. We feel like it's a girl, but will find it for sure on 11/21. How is everyone feeling? Is anyone else due May 10th too?!