I just check last month and I O'ed cd15 started spotting midday cd22 (8dpo) and flow started morning cd23 (9dpo).
This month I O'ed cd15 (but possibly cd17) and I'm now cd26 (11dpo but possibly 9dpo).
This means that yes the vitex could have just lengthen my cycle. Which would be wonderful. But a bfp would be more wonderful lol. I've not been very strict with the vitex this month though, taking it mostly once a day instead of twice, and some days skipping it completely. I know it's not great to take vitex if you're already pregnant, so I've stopped it now just in case.
My temp took a miniscule drop this morning. Pretty sure my thermy is dying, probably battery (it was cheap!!!) but it seems to be better right at this moment so I'll check temp in the morning. I usually just do 2 readings now and if they're close enough I average it and use that. This morning was only 0.02 difference so I counted it.
Last cycle I dropped quickly over just one day, the day I started spotting. So hoping that drop never comes!!