Writing Fault

Probably not writing as much as I think I have.

For example, I can write for what seems like a long time, only to discover the addition of perhaps three or four paragraphs.

It's not that I can't write a lot, I can, I guess it's just that in my head I imagine that I've written much more than on reality. Therefor chapters I write tend to be shorter, which overall may not be a problem but nevertheless irritates me.