I don't get it. You had an ich outbreak and removed all fish on February 9th. Then you added some fish back on February 28th. You said you'd take it easy but it seems like you've rushed in again. Maybe I'm misreading something but from the sound of it, you really just need to take it easy. Bad luck is one thing, but having it happen repetitively seems like human error due to impatience.
Did the puffer, angel, powder tang, and butterfly all show signs ?
When did you start full hypo?Did you already have the fish mentioned in hypo?
Its possible the remaining fish are fighting it off in hypo and will survive now that full hypo is going
QTing is a good thing
Grow your filtration