Feeling like back arching/stomach sticking out?

I’m pregnant after a miscarriage (before I got my period back) so completely clueless how many weeks I am! I am waiting for my ultrasound in a couple weeks to see how far along I’m measuring

I’ve been feeling slight nausea for about a week, and exhaustion

But as of this past weekend, I’m feeling my back start arching and stomach sticking out. This was actually my first clue I’m pregnant. I randomly felt HUGE and its noticeable when I’m walking. I thought the other symptoms were my period trying to start)

This is my 4th pregnancy. I’ve started showing early in all my other pregnancies, but this also makes me wonder if I’m further along than I was initially thinking

How many weeks were you when your back started arching?