Ectopic or tubal

I found out December 16 I was having an ectopic pregnancy. Because I was so young and had no rupture yet we decided on the methotrexate chemotherapy injections to treat it. My Hcg were never high during my entire pregnancy. (I was 8weeks) the highest they ever were was 830. I got the injections that day and it has now been 2 weeks I go back Wednesday to see if my levels have gone down to zero but I'm impatient and have been taking pregnancy tests. However my line keeps getting darker and darker. Is it possible for me to still be pregnant or have gotten pregnant right after the treatment? Has anyone experienced this?