When did you know it was twins?

I thought I was 7 weeks but turns out I counted wrong bc at my (first) appointment today, doc said 5 weeks preggo.

Now I'm asking this because if I'm only 5 weeks pregnant, my home test was positive at only 3 weeks pregnant because that was 2 weeks ago.

I took 3 home tests between two days because I was feeling nauseous and I was super thirsty all the time. All tests came back positive. Another thing to note, I took my first preggo test at night at 3 weeks pregnant and it was positive.

I'm nauseous all day every day and have been for a week now. husband says my boobies are already little heavier. I believe him bc my upper back pain got worse. I'm super fatigued most of the day and even with a nap I can still sleep through the night (I'm a night owl too so this never happened before). Body pains and full body cramps as well.

Twins also run in my family on both mother and fathers side but they are all the previous generation (my mom's mom has twin sisters and my dad's aunt has twins). Idk if they even count because they are farther back in the tree though.

I'm giving all this info because I do not know how this works. I don't know what and when normal pregnancy symptoms happen. This is my first kid in case you can't tell lol

I've low-key thought it was twins the whole time tbh so I need someone to ground me a little and tell me I'm crazy and that it isn't.