Got another negative OPK

Finally got a negative opk, and for some reason im excited, since my opk's basically told me I ovulated TWICE this month which I heard was impossible. At first I was considering March 18th my 1 DPO, because my tests were getting lighter, then they started getting darker starting on the 21st, and stayed dark until yesterday the 24th, so today is my second -this month-negative opk, so my question is, which one do I consider my ovulation AND which day do I consider my 1 DPO?