Measuring ahead at 31 weeks

So i know that it is common and in all reality it could be that i have a long torso or just cus i am bigger myself. I am 31 +5 currently and measured at 36 for fundal height today at my appt. I had been measuring at least a couple weeks ahead since about 26/28 weeks. But this is more than that and the Dr. Scheduled me an ultrasound for my next appointment to make sure everything is good and baby is growing normally. My cousin has had the suspicion that i am actually farther along since i first became pregnant. I had been trying and had a very light and weird period the month before i got pregnant and she was suspicious that i was actyally about a month farther along. Any other mommas measure ahead and actuslly be ahead? Or what was your experience i guess because this didn't happen with my first pregnancy and i was heavier then and gained a lot more I'm a little confused ol. Any input is appreciated!