Could my baby inside of me be 34 weeks gestation instead of 30 weeks gestation?

Ok. Hello, i found out i was pregnant in oct. of 2010. at that time i was told by my doctor that i was 3 months. but i haven't had an period since july of 2010 giving me a due date of april 3, 2011. I had to recently switch doctors because i believed i was more far along than i was being told. i could feel my baby move by the time i went to my 1st doctor visit. Now im at my new doctor i was given a farther due date of may 29, 2011. due to my babies size. I believe that i am 34 weeks pregnant instead of 30 weeks, my first day of my last period is july 25, 2010. haven't had a period since then. Can someone please help me out.