First of all, don't worry about being judged for abortions. Everyone has their own personal reason for abortions, and it is always the mothers choice. If it was what was best for you and the baby, then you made the right decision and there is nothing wrong with that.
With that aside, the withdrawal method is not a method. About 20% of the people who use the withdrawal "method" become pregnant within one year. If you are worried about becoming pregnant, you should look into a more reliable method of birth control. The pill is great, or if you are forgetful/don't want to take a pill every day, maybe you should try an IUD.
Pregnancy tests are accurate 14 days after you had unprotected sex, but can often take longer to be accurate. Are you using your first morning urine? Wait a few days and test again.
If there is a faint line, it is still a line, and chances are that you are pregnant. The doctors test may not have shown up because you were not using your first morning urine which is most concentrated with the hormone that detects pregnancy. Since it's been a full year since your abortion, it would not effect your pregnancy test results.