I am currently on my birth control pill when I unexpectedly start spotting, then a couple days later it becomes heavy and a large rubbery white sack like thing drops from my vagina, did I have a miscarriage?

Were you not curious enough to find out what was in the 'large rubbery white sack'? And where did this land, in the toilet? Sorry your story needs some more explanation and how would we know if you had a miscarriage from your description.

You had no discomfort, no pain from this because there would have been discomfort.