Vitex/Fertilaid question

Kristina • Mama to 2 boys & 3 step kids
I started taking Fertilaid with a low dose of vitex with it to help regulate my long cycles. Is it known for lengthening LP too? I always have a 12 day LP which means I should of woke up with AF this morning but now it's DPO 13 and no AF. BFN on DPO 10 and 11