Aw congrats sa second baby! Totoo yan na mas mabilis lumaki ang bump sa second pregnancy kasi ang muscles mo na stretched out na from your first, so mas walang resistance, a few of us moms noticed this din namin, super nag-pop out agad! But since every pregnancy is different and 7 weeks is still very early, best to mention this to your OB sa next visit para ma-confirm na lahat normal lang at hindi twin hehe, kasi they can do an ultrasound to double-check.