Mine is like that all the time. It's the position of the babies for me.
It is probably Braxton hicks contractions. They are usually painless and they are completely normal. They start pretty early on and last throughout the pregnancy. It's just your body's way of practicing for real labor when the time comes.
It could also be the position of the baby if its closer to the front or back.
No its normal, probably gas. Im 16wks also and i experience tht a lot especially when i have to tinkle