My uterus is too small for the IUD??

I went in a while back to go get the IUD birth control implant but after like 20 minutes of some seriously uncomfortable rod poking up my cervix the doctor told me my uterus is actually too small to get it. The minimum is like 7 cn or somthing and I'm 4 cm. My mother had a tilted uterus and my grandmother on the other side of my family wasn't supposed to be able to have children and she had only one. I went on the shot instead but does anyone know what having a small uterus means for your overall sexual and reproductive health? I'm 20 y/o