No embryo in the uterus, but tested positive with a pregnant test - do I have an ectopic?

Not always. Pregnancy tests measures a hormone called b hcg, it needs to rise to a certain level for the pregnancy to be seen in the uterus. Pregnancy test can also stay positive 3- 4weeks after a miscarriage. A slight rise in HCG levels , followed by a heavy period is possible too, this is chemical pregnancy. There are many reasons besides ectopic , but please consult your doctor and have them diagnose it.