I have that too. At first the doctor suspected adenomyosis, so I got an MRI to make sure. Turned out it was nothing, that's just the way my uterus is. Unless they can pinpoint a specific problem, I don't think it's anything to worry about.
I tried searching "bulky uterus" on Google, but it seems to be a generic term that Dr's use when they aren't sure what the problems is.