Feeling Discouraged CD 21

This is my second round of clomid. Last month I was shocked to get a positive opk on CD 17, this month I am on CD 21 and still no surge! I thought May would be our month, as things usually happen in May for us (first date, engagement, wedding, and our first anniversary is tomorrow). What is going on? Anyone ovulate on different days on clomid? Is there still a chance or should I just give you testing and wait for AF?