Did my baby move or is it on my mind?

I'm 18 week and I feel like I've been feeling my baby for the past 2 weeks, like a tikleing sensation, but never really know if it's the baby or my mind.. But today me and my boyfriend were playing around With music in my belly and I felt  something so hard that it even moved the phone away from the belly.. It felt like a gas/bubble, only felt it once and then felt it again 2 mins after but that deff felt like gas