Third trimester?

Ellie โ€ข Engaged to my soulmate๐Ÿ’and newly a SAHM to a 8 year old boy ๐Ÿ‘ถ๐Ÿฝ 4 year old girl and my newest baby girl born 1/25/18๐Ÿ‘ถ๐Ÿฝ๐Ÿ‘ถ๐Ÿฝ๐ŸŽ€๐ŸŽ€ ๐Ÿ’•

When is the third trimester? I always thought it was 28 weeks but glow says now that I am 26 weeks Iโ€™m in the 3rd..