What Cause Bleeding After Taking Medication After Positive Strip Test?

Hello, after missing periods for 5 days I did strip test 3 days back and found positive. Immediately I approached health centre and was prescribed 2+1 tablet dose (at 8 hours gap through insertion). I had bleeding once after the dose but then it stopped. I again approached the health centre and today the dose repeated. But nothing happened...no bleeding....I m worried