Gmail storage appears full despite no large files to remove

I’m facing a strange problem with my Gmail storage. When I check the storage management area to clear out space, it only points out small files of about 20-30mb for deletion. Yet, my storage is completely full, and I can’t get new emails. I’ve searched my sent items, trash, and spam folders, but nothing explains the large amount of space being used. Has anyone experienced this issue? I’m confused about what is consuming all my storage when the cleanup tool isn’t highlighting any significant files. Any advice on tracking down and eliminating whatever is taking up all this space would be greatly appreciated.