I'm so confused. I've been using clearblue advanced digital ovulation test for the past 10 days, well I ran out & my SO didn't feel like buying another expensive pack so I told him I'd tried the cheap ones from the dollar store. With clearblue I got high fertility for 7 days straight now (last one I took was this morning with FMU) & I just got back from the store & took the cheap test & it's says I'm not ovulating....? Should I stick with clearblue? Please help