Pregnant, or medicine?

That is the question. So, the injection I got (called Profasi) has HCG in it.. the stuff that turns a pregnancy test positive. So, obviously, the medicine will turn a test positive if taken too soon after it's administered. To see how long it would take for it to get out of my system, I started taking home tests at 6 days past the shot. That day I got a light but definite positive result. Obviously the meds were still there. So I waited and retested at 9 days past the shot and got a blotchy, dark, shadowy line in the test window.. I'll stretch it and call it a faint positive. I figured if I waited two more days and retested I'd get a true negative result. That was today. Instead I got a faint positive. It was a darker line, visible but not very, but I was surprised as heck to see it. So, now the question remains.. remaining medicine doing this.. or early pregnancy. I have no way to know right now. I plan to retest Monday.. SURELY if I'm not pg I'll get a true negative result by then... I have a blood test Tuesday. I hate those.. the results are so final! lol Pray for my sanity! This is a bit hard to wrestle with in my mind.