Pregnancy due date

So I haven’t had a period since December 4th and I found out I was pregnant this weekend just gone so it would have been the 26th Feb, I went and had my first midwife appointment today no scan just an appointment and she’s putting me at 12 weeks 2 days, im just worried because I’ve not had any symptoms or anything I only thought too test as I do every few weeks because I have irregular periods anyway I always have, is there a chance I’ve ovulated without my period and not realised?and I am early on?

Or am I actually 12 weeks and just in denial 😂😂