Big Uterus

Today I Went To The Doctor (obgyn) For A Pelvic Exam And She Told Me I had a big uterus and then she gave me a preg test which was negative I am sexually active and my partner comes inside of me every time but I'm just a little threw off by the big uterus is there something wrong could I be pregnant and it didn't show on the test.? Btw I never been Prego before has this happen to anyone else