Supply decrease

I EBF my baby, sometimes give him a bottle so he knows how to take it. All was well up until yesterday when I noticed I don’t feel my letdown anymore. I have had a very strong letdown and also can pump 3-4 oz after a feeding. Haven’t pumped in 2 days which is normal for me. I don’t do it every day since he doesn’t allow me to. Decided I would tonight because he hadn’t ate on one side for 2 hours. I only got 1 oz total from both sides. Had to also give him that ounce because he woke up crying after I fed him and put him down for bed. I’m PANICKING about this. Afraid my milk is drying up all the sudden within 2 days. How did I go from being an over producer to this?!