When is second trimester confused?

Inessa • I'm 26 years old , I'm currently self employed, I am married to an amazing man! We have a beautiful baby girl that was born under a pound. At 26 weeks , I am currently pregnant with baby number 2 ♡
I am 12 weeks 1 day, glow app telling me I'm in my second trimester, I thought second trimester not till week 14 ?