Stress over weight %iles

We just had our 2mo peds appointment and our LO has dropped from 13th %ile at 1mo to 8%ile at 2mo. He's maintained 28%ile for height and is up to a whopping 96%ile for head circumference, but we're all concerned about his weight gain. I EBF and my husband gives 2-3 bottles of pumped milk during his shift at night.

The pediatrician suggested I follow up nursing sessions with pumped milk. He's a spitter too, so I'm also supposed to be keeping him upright for 30min after every feed. How on earth am I supposed to nurse, pump, give a bottle, and hold him up for 30min every 2-3 hours? I'm so anxious about his weight gain. It feels like every other baby I know that's his age is chunky and everyone we see comments on how small my LO is. I swear he poops and eats like crazy and I hate feeling so stressed when I'm the one producing all his food.

I'm following up with a lactation consultant to do another weighted feed as soon as we can... but looking for external reassurance. Anyone else had a skinny baby and get back on track without supplementing with bottles & formula? At what point can we stop caring about %iles and feel confident that he's happy and healthy?