If you’re having twins, would you see them by 7+1?

I have the strangest feeling that I might be carrying twins, and they do run on my mom’s side. I’m not having any crazy symptoms, just an intuition I suppose. My question is if I am having twins would my doctor for sure be able to tell at 7+1 or do they sometimes get missed that early & seen at a later ultrasound (if that makes sense?).

Edit: I haven’t had my first ultrasound yet, but I will be 7+1 when I do!