Positive but how ???

Back in may 2020 i had a miscarriage. I had a positive on 12/29/20 but days later had a full blown period and my tests were very very faint and digitals were negative. My doctor told

Me it was likely a false positive. My period was due today and i felt dizzy so i decided to test (especially since my friend was supposed to come over tonight for drinks). We were preventing the whole month of January so I’m really confused right now. I’m waiting on a call back from my ob doctor but 🤯🤯🤯 I HAVE NO SYMPTOMS except a little dizziness that started a few hours ago. Someone help me understand this