Opk question.. Help me figure out how many dpo I am please!

So I was taking two brands of opks starting at cd5; Internet cheapies and first response digital.  I got two solid lines on the internet cheapie on Monday afternoon (2/15) and again Tuesday (2/16) morning but negative that night.  During those times I got a bfn on the first response.  On Wednesday (2/17) I got my bfp on the first response.  When do you think I ovulated?  Trying to figure out exactly how many dpo I am.