I have been experiencing mild-cramping pains in my uterus area during and after I have intercourse

Its not a very agonizing pain, however, it feels like my whole uterus is being pushed up and down inside me, causing a discomfort feeling in my abdominal area

Afterward my uterus/abdominal area seems to ache and feel cramped up for atleast 30 mins- 1 hour

I have spoke to my doc, and she said its fine having intercourse during pregnancy.
But it has me a little worried as to whether or not these cramps and pains are normal?

( we arent doing it heaps rough or anything. And its only sometime that it feels really bad. Usually when we go longer without sex and then have it.)