I have took abortion pills a week ago. i didn't have any heavy bleeding, just normal periods and few clots for only few days. could that be a sign that the process was unsuccessful? i was three weeks pregnant?

Based on what you describe it’s possible that it was successful but also potentially not. The only way to know for sure this early is to do a blood test called an hCG titer and then repeat it in 48 hours if the test is negative or falling it was likely successful. A year and pregnancy test will still most likely be positive at this stage even if the pill was successful