I had a blood pregnancy test done at a lab and it came back positive, test was repeated the next day and the doctor says it is weakly positive?

Tests are accurate: There is no question posted but merely a statement. That said, today's pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, vaginal spotting, or medications. A blood test gives a reliable result 2 weeks after sex (2 weeks after when conception might have happened), or just after missing a period.