Help with BBT

Hi, I have many doubts about my cycle and BBT, the more I read the more confused I get, can anyone help if really know pls:

- Is it ok my BBT decreased during my period?

-Is it normal BBT increased after period ended?

-Should I have sex now before BBT increases even when not yet ovulating?

- Is it normal ovulation seems to be so close after my period ended?

Appreciate your help, I'm trying to figure this out!