How accurate is BBT?

Lisa

I didn’t test for ovulation this month, but going by predictions, I am 14dpo, on cycle day 30, AF always arrives 12 - 14dpo and my cycle is usually 26-29 days. But, based on BBT I ovulated 4 days later, which would only make me 10dpo, cycle day 26. Also I’ve always had a temp dip the day before AF arrives, but it is increasing instead? Should I be going by BBT?