Haha relatable! At 21 weeks it's still quite early, so yang you rasa macam butterflies or bubbles tu very likely baby gerak tapi sebab first time lagi so susah nak distinguish from gas . The way to confirm is if the movements jadi consistent and in the same spots, then you tahu definitely baby, a few of us first-time mums realised pastu once we felt it clearly a few times, we baru confirm "eh yeah lah that's the baby!" Usually around your second or third trimester the gerak becomes unmistakable, so don't worry, you'll know soon enough once baby gets stronger!