If you're unlucky to not live anywhere near a flower meadow so rely on one spawning in a swamp, you're gunna be waiting a while, checked 7 swamps, i have double what i need to see them all (according to wiki) and didn't find any.
There's a lot more biomes in the game now than when camomile was introduced, and the item isn't exactly OP, so imo the spawn rate should be buffed somewhat so its not "super rare" on swamps. I would have expected to find atleast one after checking 7 decently sized swamps tbh.