Abortion Recovery help

Please only individual who have experiences that can help me with my question. Had an abortion on 12/5 and still testing strong positives 8 weeks later. Nurse keeps telling me it can take months to get my period back and for me to stop testing positive given that I am breastfeeding. I just find this questionable as I was told originally that I would stop testing positive after 6 weeks. I have not had sex since my operation. I guess I’m freaking out that the abortion wasn’t successful. I have been feeling sick but i know stress worrying about this could be playing a part. My stomach isn’t hard and if I was still pregnant i would be almost 15 weeks and i don’t have a bump or anything like that. If anyone has a relatable I would greatly it. Thanks ladies. And before anyone says use protection next time, I am on birth control and was thoroughly shock.