I had a brainwave and checked that info that comes in the pack - dunno why I didn't think of that before lol. Apparently it doesn't stop ovulation, it just makes it harder for sperm to reach the egg, and makes the uterus unfavourable for implantation. So I guess if AF comes back it should still be doing it's thing.

For some reason he said it's usually fine for the first 6 months and can be less effective after that?