So this does sound like you had a major conversion of CYA into ammonia and the chlorine you are adding is creating and partially destroying CC. If you look at the post I linked to earlier for the timeline of when this happened to me, you'll see that there was CC and a huge chlorine demand. The bucket test is your easiest way to determine how much more chlorine you will need. An ammonia test might also be useful, though you might not measure that much now given how much chlorine you've added.

I wouldn't add more CYA until you are able to keep the FC from disappearing so fast. With no CYA, FC should drop in half in about an hour but you shouldn't be losing much overnight. Right now your loss rate is much faster than that so you are still getting rid of ammonia, monochloramine, and partially oxidized CYA. Unless the FC is able to stay above zero, then bacteria can still survive and consume the CYA you are adding -- you're giving them a nice meal!

You can see that prevention is far easier than having to deal with this. Making sure the chlorine level never gets to zero (certainly for no more than a few hours) is key. Closing a pool as late as possible so that the water is cold and shocking with chlorine and then opening as early as possible in spring with the water is still cold will help prevent this from happening again.