Provera / Prometrium

I had my first miscarriage in January. Two periods since were 31 days on the dot. Now I’m 11 days late and negative pregnancy tests. My OB prescribed the above medicine but my hubby and I leave for Greece next week and don’t want to have AF come during (since originally I should have been ovulating) 😭

Has anyone taken this before and have advice on when to start, how your period was with it and if you got lucky to conceive after?

Thanks :)