forget the ectopic pregnancy. The tests are for hCg, the pregnancy hormone, and that begins to rise upon implantation. There are other symproms for the ectopic pregnancy but not the home pregnancy tests.
The test used by the doctor is likely a blood test and it is more sensitive and more accurate than the home pregnancy tests using urine. They should, however, show the same a few days after implantation of the egg in the uterine wall.
This is convoluted but a possibility: The egg partially implanted and triggered the production hCg giving positive tests both at home and with the blood test at the doctor's office. Then, the egg was sloughed off and the production of the hCg ceased. The blood test would be sensitive to the stopping of the hCg almost immediately and would show "not pregnant." The hCg in the urine would take a day or so to fall below the sensitivity level of the home pregnancy test, so the home tests would still register "pregnant."
You are dealing with different sensitivity and different time lag in the showing the hCg in the blood and in the urine. Hence, the confused results. Wait a couple days until another home pregnancy test. It will likely fall in line with the negative blood test.
Posted: 30 Sep 20:07