6 weeks is pretty early to be able to see anything. I wouldn't worry. I had an ectopic in December. The tube ruptured, massive hemorrhaging, almost died. Lost that tube and the ovary along with the baby. I got pregnant sometime in April. Don't worry. You're alright. Just give it time and watch for symptoms of another ectopic since having one makes us more likely to have another.
When I was 6 weeks pregnant the Doctor seen my baby it look like a small black dot.... But it also can just be tooo early! Good Luck!