Your converter should not have been that tight. My guess it that it was not fully seated and you either ripped off the tangs on the converter or damaged the pump. Thats a hard and expensive lesson but I bet you only do it once.
I think you are correct. The converter did spin freely until I got the trans and engine mated. So maybe it was all the way back even after the 2nd "clunk". It definitely sucks, because it was a brand new torque converter. But, can't buy experience. Won't let this mistake happen again.