Ectopic Pregnancy?

I have been having extream pain for 4 days in my lower left abdomen. I went to the doctor and they told me I was a week or two past conception. They said they couldn't see anything on my ovary, but that they did see some fluid in my uterus, but could not see a baby in the fluid due to me being so early in pregnancy. Has anyone else found out about an ectopic pregnancy incredibly early in pregnancy? I have two days until my next ultrasound. I am six months postpartum and had a miscarriage before my baby was born. I am terrified of losing another baby.