United have gone seven matches unbeaten across all competitions, though their run included an FA Cup exit on penalties to Fulham.
Despite this positive spell, they remain 13th in the Premier League, 12 points adrift of the top four with only nine games left to play.
After the international break, United return to action with a tough away fixture against high-flying Nottingham Forest on Tuesday.
April will be a defining month for Amorim's side, with seven matches, including a Europa League quarter-final against Lyon and key league encounters against Manchester City and Newcastle.
"I'm really confident. I feel that the players are more confident, the energy is different," said the Portuguese manager.
"But I also know that this could change with the results. So we are focused on maintaining the energy. We worked on some things that we have a lot to improve.
"Even winning the games, we can acknowledge that we have a lot to improve. But we are in a different moment, more confident and ready for this final two months of the season."