Here's how you know you've become a true mommy.
Your baby spits up and somehow aims it down your shirt. You first wipe him off and make sure he's not too traumatized by the whole event (he absolutely hates spitting up). You then just pat the shirt to absorb the spit-up and go on with feeding/changing/tickling/rocking/etc. your baby. Some time later in the day, you realize that you are still wearing the same shirt and you have a clump of dried spit-up caught in your bra. You also realize that you don't really care because changing the shirt or fussing with yourself would have meant moments away from your little guy while he was awake.
Oh yes, I have arrived.