Amorim says he cannot afford to lose the likes of Kobbie Mainoo at this stage in the season.
He said, "It's going to be hard for someone to leave the club if we don't get a substitution.
"We are short. Even with the full squad we are short for something that can happen.
"We are a club with a big responsibility. We are dealing with all these issues and in (the media's) heads, in my head, in everybody's head, we need to win every game. It doesn't matter. There are no excuses."
Amorim also said: "We are struggling in this moment, but the club has a plan and we are going to stick with the plan.
"If we have the opportunity to bring a player that we think is going to be the future of the club, is going to come. If not, we have Jack (Fletcher), we have Shea (Lacey) - in three weeks we'll have Amad, Noussair (Mazraoui) and Bryan (Mbeumo), and the return of Bruno (Fernandes) and Kobbie Mainoo."