How long after your miscarriage, did you get positive tests?

My 2nd baby just turned 1 and was exclusively bf so I just got my cycle back on the 12th of December. It was incredibly heavy and lasted 10 days. I thought it was just bc it was my 1st cycle. I took a pregnancy test on the 26th of December (I have no logical excuse for taking it, I have a problem lol) & it came back pretty positive. I continued to test and the line gets lighter and lighter. But it's still very obviously positive. I'm so confused and honestly, super upset bc I have no confirmation about anything right now. 😕