HCG Numbers

y’all im confused. I had a positive blood test on monday, but the number was at the low ended of positive (7) so my dr told me i had to go back wednesday to see if the number doubled. So i go wednesday and the number did not double, it only went up by two (to 9) . So the the doctor called me and said that the pregnancy most likely isn’t viable and to stop my progesterone and to come back friday to make sure the number goes down. He also told me that once i stopped the progesterone the number would drop to 0 pretty quickly and he had anticipated it would be zero but today. I get the call today with my results and my HCG doubled from what it was on the wednesday (so now it’s 18). They didn’t really tell me much more than they want me to come back in Monday again for more blood work to see if the number drops. Has this happened to anyone else? I’m so confused with what’s going on right now lol