Plug-In Baby

My son has started to make an o-shape with his mouth when he’s expecting his bottle. I feel like I’m plugging in my iPhone or something into the socket as I slide the nipple of the bottle over his lips. Except instead of charging the bottle, we’re charging the baby. He drains the milk out of it like it’s a battery, and he’s powering up! My wife asked how we know he’s actually drinking and not just sucking on the nipple. I told her to look for the charging light to turn from red to green.