Positive ovulation test but faint line on pregnancy test

I recently had a miscarriage on 3/12 at 11 weeks 5 days and had a d& c on 3/13. I stopped bleeding a few days ago. I find it odd that my ovulation test is positive but I have a very faint line on a pregnancy test ( I'm definitely not pregnant as we just had sex yesterday for the first time since I found out I miscarried). I have two other children so I know that when you are pregnant and the line is super dark on a pregnancy test typically an ovulation test will also be positive. It's weird I'm getting a positive on an ovulation test but still a faint line on a pregnancy test. My doctor did a pregnancy test on Wednesday and it was negative but my tests at home are more sensitive. Is it possible I'm ovulating already with a very low level of HCG still in my system? I'm 19 days post d and c.