I measured 3wks big my whole pregnancy its perfectly fine atleast thats what my doctor told me lol

When they measure your stomach with the tape it should be the same number as you are weeks, so if you're 28 weeks your stomach will measure 28, sometimes women measure a little bigger and that could just be because you have a lot of amniotic fluid, not that the baby is measuring bigger, they can only tell that with an ultrasound and even that is a guesstimate. I wouldn't worry too much, your fluid levels can fluctuate especially if you drink a lot of water.