To feel insignificant or see oneself negatively. After that disastrous meeting with my boss, I've never felt so small in my life. He is such a jerk and always insults her so that she feels small.
look/feel ˈsmall(also feel ˈthat high) feel stupid, embarrassed or ridiculous in front of other people: Why did you tell everyone that I’d failed all my school exams? I felt so small. ♢ Mrs Jones made him feel that high when she criticized his work in front of everybody.
When using the expression feel that high, you often use your thumb and finger to indicate something small.