All three sentences mean almost the same thing, but their -tone- and "context" differ slightly. I’m not at ease. You use this when you feel uncomfortable in a situation, usually socially. Example: A formal meeting, a new group of people, a tense atmosphere. I feel uneasy. You use this when something doesn’t feel right or makes you nervous inside. Example: A strange noise at night, a worrying message, a bad feeling about something. I don’t feel at ease. Same meaning as “I’m not at ease,” but a little softer and more polite. Example: When you want to express discomfort without sounding too direct. Teacher’s Tip “At ease” is about comfort in a situation. “Uneasy” is about inner nervousness or worry. If it feels social → “at ease.” If it feels emotional or instinctive → “uneasy.”

We use these when we feel uncomfortable about a situation. "My boss asked me to take the lead in the team discussion today but I'm not at ease speaking in front of a group that big." "I know that we will have to fly to get there, but I feel uneasy on long flights." "I don't feel at ease at those conferences. There are too many people that I don't know."