My period changed since 30, what's my day 1?

Alison • Finally pregnant after 5-1/2 years and losing my mother on 11/1/18. I got pregnant the week she died and just before my husband got a vasectomy. I never thought it would happen for me. Life sure is crazy!
I have always spotted 2-3 days before my periods but it was usually the brown spotting. Since my 30's my period has changed. I still spot 2 days prior to an actual flow, but it's usually one day brown the second is red the third is a heavy flow then it's back to very light flow or dark spotting for 2-3 more days til I'm done. 
I'm so confused as to what my day 1 is anymore!! My fertility doc says first day of actual flow, my OB says first sign of red blood! What do you ladies go by?