Expecting multiples? Or normal second pregnancy?

I recently discovered that I'm pregnant, which came as a bit of a surprise. I had suspected something early in March, and took a test on the 9th. That test came back negative, so I brushed off my initial feelings. A few weeks later, I was putting my toddler to bed and he pushed off of my stomach to get comfortable. He does this quite a bit, but this time it hurt in an odd way. So the morning of the 29th, I took another test and that one did come back positive.

Given that it's such a small window, I feel confident that I can't be more than two months pregnant at the very most. I'm schedule for my first appt at the end of the month, so I'm hoping to get additional confirmation around then. The strange thing for me is that Ive been experiencing symptoms that I don't remember feeling with my son, especially this early.

I started having back pain and a dull ache in my stomach that is pretty constant. The ache doesn't feel internal, it's moreso that I can feel my skin stretching. I've searched round ligament pain, and I don't think that's what I'm feeling since it's not a sharp shooting pain on the sides of my stomach. The pain covers my entire stomach and is just a constant dull ache. On top of that, I feel like I can already view a small bump which seems insanely early considering that I'm 2 months at most.

So my question at this point is moreso for mom's of multiples. Did you notice any of the above symptoms as early on? Or for mom's who've been pregnant multiple times, does this just sound like a normal second pregnancy? I know every pregnancy is different, and that I won't be able to confirm anything until my first ultrasound, but I figured trying to get some community feedback might help.