I'm sorry you are going through this. But Cassady on here had a m/c and got pregnant in the same week. I think it's a good idea to have blood work done 2 days apart to see if your numbers are rising or lowering that way you can know for sure if it is a new pregnancy or not.
Just treat it like a new one until you know for sure, better to be safe than sorry.
Good luck!
I also think it's the old HCG in your system. I had a miscarriage as well and had a D&C July 1. A week after my D&C, i was still getting positive hpts. I'm STILL waiting for AF. I thought i felt ovulation pains about 2 weeks after my D&C but i never got my period. about a week ago - i think i really ovulated. I had tons of EWCM and ovulation pains and i took and OPK this time and it was positive. I think my body was so stressed from the miscarriage and the D&C that it might have been gearing up to ovulate 2 weeks after the D&C but never did and then 2 weeks after that, finally i had ovulation... or i hope i did. Anyway - this might just be my body and not what you're going throught but it seems really soon for you to be pregnant and getting positive tests already but good luck and keep us posted.
If you had a miscarriage August 2, that would count as a period as well. Typically, we ovulate about 2 weeks later, that would put us as August 16. There would be no way to know right now if you are pregnant. Wait until your first missed period (about 2 weeks away) and do a blood test. Still then, you would have to do another blood test to compare results and see if your numbers are rising. It's very difficult to determine pregnancy when you do get pregnant right after a mc - one of the many reasons why doctors say to wait at least one cycle to ttc again after a miscarriage. I know the wait is hard (I had to wait almost 3 months after my mc to ttc again), but the wait is well worth it to make sure your body heals, know where you are in your cycle, and to have a better chance of not having ANOTHER miscarriage.
Also, it takes some people longer than others to get rid of all the hcg in your system. Some people only take a few days, and others can take up to six weeks (like me). The average seems to be around 2-3 weeks to completly get out all of the hcg from your system. If you did the metho shot, it takes longer. If you had d&c, it takes a shorter time. If you had a mc naturally, you should fall somewhere in the middle.
I would assume the +hpt you are getting is from old hcg in your system. If you ovulated around cd14, it still takes about 9 days for the baby to travel down, implant, and your urine to start picking up the hcg again. According to your dates, you are a bit early for that.
I hope that helps to answer your questions!