Is it possible to be pregnant a week after a miscarriage? Advice please.:)

I had a miscarriage ,but I thought it was my period. I had the miscarriage when I was supposed to have my period. So after I stopped bleeding, I BD because I got a positive ovulation test. This was a week after the miscarriage. The miscarriage was at 4-5 weeks. It was a chemical really. The doctor confirmed that it was a miscarriage by blood tests. Now, it's 1.5 weeks after I ovulated. I feel so tired and have back pain. These are the same symptoms I've had with my other pregnancies before a positive test. 

Vote below to see results!