OPK Question

La

Is it normal to have several days of strong positive OPK'S? I'm on day 3 of very strong positive tests and this morning the test line was pulling from the control line, first time that has ever happened for me! I'm on CD 21 though and starting to worry a little that I may be anovulatory this month. 2nd month off birth control pills and last month I O'd around CD16 confirmed by BBT. Top OPK is yesterday and bottom is this morning.