5months after misscarriege.

I miscarried 5months ago. And bin taking cheap ovulation tests and they don't seem to be working... Or I can't read them. Well anyway I've gone out and got 30clearblue ovulation tests. And don't no when too start using them my doctor told me that I will ovulate between the 13th. And 17th I don't understand whether he ment 13days from the first day of my period or 13days from the last day of my period..? I came off my period at around about 7lastnight was on my period for 5days and my cycles last 27days can anyone tell me when to start using them as am really confused?x

You ovulate usually 14 days after the first day of your period.
You could start using them now, if you just came off your period, I guess.

start using them on day 12 or 13 from the beginning of your last period. Make sure that you take the test in the middle of the afternoon and make sure that you haven't pee'd or had anything to drink in at least 2 hours.