Months

From this picture I am 6 months. I am 22 weeks today. My fiancé's grandma is fussing with me because she's counting by the calendar and says because I am not fully 6 months I can't say I have 3 months left. I told her that I say after this month, I have 3 months left till I'm due and some how we are both logically right and she won't stop fussing with me about it. I say that I am 6 months because I am in the beginning of my 6th month! After this month, I have 3 months left! 7,8,&9 months! But she's dragging out the slender and says I can't say I'm 6 months because I'm not at the end and a full 6th months. She says I have 4 months left because she started counting my weeks at today and she's counting 6,7,8&9. Who is right?