Have 0 idea when my last period was

Last month was quite a blur my husband and I had a death in the family and we’re super depressed this past week I had nausea all week thinking it was a stomach bug I treated it as such not thinking anything of it. My husband ended up ordering a test and I got my BFP however I have 0 Idea when my last period was or when conception could’ve occurred. Not sure what to tell my dr, my last 2 babies we were trying so I remembered my cycles but not this time 🤦🏽‍♀️ pregnancy