I'd lean towards thinking this is AF. Looking at your charts, granted your temps haven't fallen below coverline, but between the fact that they have fallen and you tend to have a short LP, it looks like the main reason for a shorter cycle is because you O'd earlier than normal.
Me (30), DH (31), DS (3.5 yrs - 5/07), DD (1.5 yr - 2/09) via VBAC!!! DS (newborn - 11/10) via natural VBAC! 2 angel babies - 06/06 & 04/08