How to tell?

I'm a FTM, 16w4d pregnant and my stomach makes weird feelings. How do you even distinguish between the baby flutters and little kicks, to other things going on in your stomach? 
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I felt just felt random popping like in my stomach, thinking it was nothing, which it probably is. Then I poked my belly a few times, then i had that "popping" feeling for a quick second 
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Anyways, how do you know if it's your baby moving or just your stomach doing weird things?