1996 Oldsmobile Ciera Collapsing Gas Tank

I am not sure yet but I think that my Gas Tank might be Collapsing. I have heard several years ago that a gas tank can start to Collapse if the vapor recovery system is blocked off. This car once had a 22 gallon tank, now it will only take 17 gallons after it ran dry, and that was the first time I ran it dry, because I knew it had not gone the distance from the last fill-up. I just taught my gas gauge was going bad.

Dos this make since?

I became confused the Gas Tank was OK. The car's Tank is only a 17 gallon tank to began with, but I got it confused with another car I once had. The Gas Filter was all plugged up which became a much grater problem after running out of gas.

Thank you