I was told I was a certain amount of weeks than just last visit when I was 25 weeks the dr. Told me I was measuring 28 weeks ! I just don't get it does that change my due date which was march 18th or does that means I'm just gaining a lot more belly weight and it appears I'm measuring bigger ?? Today I just turned 27weeks (far as this app tells me) but am I really 29-30 weeks? So confused .