2 positive tests then two negatives

Has anyone had this happen? I tested positive (hubby confirmed and bff confirmed) the day before and after af was due. I then re-tested twice yesterday on a digital with fmu, -, then dollar store cheapie, -. Granted, the dollar store cheapie was very diluted due to drinking lots of ginger ale (morning sickness is kicking my butt ugh). I dunno what to think bc my symptoms line up. Any thoughts? Per my lmp I'm 6 weeks today. However, I think I'm btw 4-5 bc I O'd late.