Positive test after abortion

Hi i had an abortion on the 23rd November and they told me to do a test on the 15th dec i have done this and its come back positive still although one line is strong and the other line is quite faint.... i had heavy bleeding for a week after and then it slowed down and now im just spotting every now and then i was bleeding at the time when i did the test....what does this mean and what do i do now??