Ok I know it is not really that important but...

Three different sites have told me three different things! The starting date of the second trimester is

12w1d, 13w1d, 14w0d. What the?

Does anyone know for sure when it starts? I want to be excited and feel like I have passed a milestone but I am not sure when it is.

Also.... some sites say that when you are 12w3d, that you are 13 weeks. Is this right? I would say 12 weeks.

Again, it is not really important, just frustrating! And when I track bean's development over time I would like to be looking at the information for the right week!