feeling shame

regretting, remorseful

shy (the usual word)

shy

awkwardly self-conscious; (feeling) foolish or embarrassed because of having done something wrong

shy, embarrassed

(of a person) self-conscious and uncomfortable in the presence of others; (of animals etc) easily frightened

quiet and self-conscious

(used as a form of apology saying one is) feeling unhappy and disappointed with oneself for something one did or did not do

remorseful, regretful