Trigger warning miscarriage

 four weeks ago I had a missed miscarriage. I was supposed to be nine weeks pregnant,  but growth  stopped  at six weeks, my doctor, gave me the OK to go have sex and try again if I was comfortable with that idea, I had sex with my husband on 7 January and he cum in me ,  January 8 I took a pregnancy test and it was negative just to make sure I would be able to track a pregnancy if it took place since my midwife told me I’m extremely fertile today. I decided to take another pregnancy chest just to humor myself, and I got a slight positive.,  could I already conceived now since I’m extremely fertile or could this just be my hormones still coming down from the miscarriage four weeks ago? I just don’t understand why are getting negative test on the eighth and a positive today on the 10th could I be pregnant again?