This is my second DC. When I was pregnant with DD I started to feel what felt like little bubbles around 17/18 weeks.
I'm only 13 weeks but have occasionally already felt a similar bubble sensation. Also I was sat in a meeting yesterday so wasn't even thinking about it. When I can only describe as like something flipping around it happened twice. Could I already be feeling my baby move at 13 weeks. Or do you think it's all in my imagination as DH seems to think or possibly gas