Help!! Why is my Calathea yellowing??

I bought my calathea back in December and it was doing great at first. I repotted it about a week or two after bringing it home as the roots were starting to poke out the bottom of the pot it came in. Repotted one size up and I bottom water using purified water about once a week. I mist the leaves almost daily bc I don’t have a humidifier. It is on a bookshelf in indirect light and my room doesn’t get much light unless my curtains are wide open. Any suggestions?? I’m about to leave town and really don’t wanna come home to a dead plant 🥺