Just had a baby in January, I'm breastfeeding (one period at 4 weeks postpartum and haven't had any since) and I've been on the mini pill with no spotting. I have no clue when I would have potentially ovulated. All of a sudden I feel pregnant again, so I tested yesterday and got incredibly faint lines. Tested again today and no lines? I even used my first pee for on the FRER and generic from this morning. Could I just be super early? Is this a sign of a chem pregnancy or tubal? What are the chances of a false positive?

Yes, the lines appeared within the timeframe on the first three.