Why do I look pregnant ??

I was pregnant beginning in January with the IUD but had surgery for removal since it turned out to be a molar pregnancy. My HGC levels are finally zero as of this month (August) but my lower belly looks so round as if I’m 4 months pregnant. Due to the molar pregnancy I had to get on a different birth control and I have gained weight on this Depo shot so I will be switching off and back to the IUD. I don’t drink alcohol often or eat fast food can some one explain why I look pregnant. This would be my first pregnancy so I don’t understand if that changes my body.