Toddler teeth advice

Valeriya • PCOS.... miscarried 1 pregnancy and momma to a baby boy 💙

We brush at least once a day usually twice a day. His pd said it looked like fluorosis but now it’s on 4 teeth. Any advice on what this is? I hope it’s not cavities or decay… she said we didn’t need a dental appointment till he’s 2 but I think I’m going to go ahead and schedule one tomorrow morning.