How far along?

I’m confused how to tell how far along I am since my period was messed up, my last period was nov 1st and ended around November 7th/8th. We decided I wouldn’t go back on bc and we would TTC once my last pack was done, which was middle/end of November. Didn’t get a period, ovulated on the 1st of December according to opks, and got positives one December 12th. Doctors keep going by my last period but I never got positive opks till December 1st. Would I go by ovulation to tell how far along I am?