Very low HCG but doubling + spotting

I know this probably gets asked a lot but anybody had a very low HCG that was doubling and had spotting (mostly brown with reddish after bowel movement) but went on to have a healthy pregnancy?

If my opks and temps are accurate then HCG was at 7 on 15 dpo (negative hpt on 12dpo, clear positives on 5 different brands and 2 digitals on 15dpo) and progesterone at 3.4 (low i know), doc called in the evening of the same day i had second bloodwork done which was yesterday and said most likely a chemical. But i Got my second bloodwork results today and it was 15 (17dpo) so it doubled in about 40hrs. We never repeated progesterone. So today when i called, doc said wait a week and if I'm still not fully bleeding by then, then we'll repeat bloodwork since its still most likely still a chemical. Dont have high hopes but would appreciate others experiences