Hi
BF will do this kind of thing. Plus I noticed that Jack is now 6 months.
Alot of girls who BF find that AF stays away until 6m or even longer. So this is what it could be.

Just remember that every one is different, this may be just the way your body is adjusting after the preg and birth of Jack.

I agree with you about keeping the diary for a little while longer and if it keeps playing up go and see your GP. If you are seeing a clinic Nurse for Jacks weight/measurements ask your Nurse as she will have alot of knowledge about AF and BF. Clinic Nurses are a wealth of knowledge just waiting to be asked a question.

Good luck with eveything
Take care
Chris