What Can Cause Bulky Uterus?

hi doc,i am 37 year old and i gave birth to baby before 8 months after 3 months of giving birth i had heavy periods along with cloths,i thought its normally happan aftr dilvery but yesterday i went to gynocolgist and she told me aftr examination tat i have bulky uterus.In my ultrsound report: Utrerus appear normal in size,with normal shape and contour,its retroverted in postion.92x56x55mm.No mass lesion is seen.CET IS 11MM.RT.OVARY APPEAR NORMAL,LEFT OVARY APPEARS NORMAL,FEW FOLLICLE IS SEEN IN BOTH OVERIES AND THERE IS NO ADNEXAL MASS.NO FREE FLUID IN PELVIS. now i am very much worried about it also i wana be pregnant again soon,why did my uterus get bulky or does it any seriouse matter? pls help