I'm not sure if I got your problem right. I try to help you by providing you with some examples.
The invoice amount is to be paid in full.
This book is full of errors.
He thought about it all night full of despair and longing.
You use less to modify a singular noun.
The job is less difficult than I was told.
You use fewer to modify a plural noun.
I have fewer essays to write than last year.
Does that help?
Student or Learner