Storage

Why is it that even though I purchased extra storage (200 GB) it stills shows I only have 128 GB and I am full and cannot do anything on my iPad? Two days ago I did not have any problems. Now, suddenly, every time I try to do something it says storage full do you want to manage settings? All I can do is delete more apps and nothing changes. I already deleted half my apps, most of my saved email, and many of my Word documents, and purchased extra storage, yet and it still shows the same amount! I read somewhere that the storage I purchased is not the storage in settings. Someone please explain this to me. Thank you!