Probably from bloating. =)
The baby is way too tiny for you to be showing. It's bloating!!
I'm 7-8 with my 3rd and I'm the same boobs gone up 2 cup sizes and look 6months ! I was tiny with my other 2 both girls x
Went to my ob appointment and its not bloating this is my 3rd child and my body is ahead of itself the baby measures a little bigger then six weeks but have to wait for a more accurate ultrasound in 3 weeks