We are trying for a baby and thought we had the fertile dates in hand. My GF came off the pill in May and has started her period on 27th of the month in June and July. But she started her period on 22nd of this month (Aug) but only lasted two days. We thought it might have been the implantation but we believe perhaps it wasn't. But it only lasted 2 days?
Pregnancy test showed as negative but maybe inaccurate as test should be taken 27th of this month assuming she doesn't come on.
We know periods can start early but the confusing aspect is it lasted two days. We don't know the cycle amount now too!
Firstly, this is in the wrong place, it should be in Conception.
Secondly, if your girlfriend only came off the pill in May, it's too soon to predict her cycles. It usually takes a few months at least for them to get back to normal and for your girlfriend to be able to predict with any accuracy when her period is due, let alone when she's due to ovulate.
I suggest that she uses a cycle tracking app like Clue or Ovia. There are also signs of ovulation she can look out for.
But in the meantime my best advice is that the female body is a mystery and your girlfriend might have long cycles, short cycles, long periods and short ones - it's all part of the TTC journey when coming off the pill.