I Had My Left Tube Removed On May 1st Of

I had my left tube removed on may 1st of this year because of a tube pregnancy and 3 months later ( Oct 1 of this year) I had another tube pregnancy on my right side and had to have that one removed... while two weeks after my surgery me and my husband have been having sex with no protection ...I havent seen my period since the surgery and I'm very concerned because I have been feeling very sick on the stomach every morning I get up out of bed... could I still be pregnant because I was only three weeks before the surgery and the fact the doctor wasnt able to see anything on the u/s then..so worried I don't know what's going on with anything.. please help