Full of yourself
Meaning: to think that you are very important, conceited, self-important. (*Typically: act ~; be ~.)
Example: Mary is very unpopular because she's so full of herself. She doesn't care about other people's feelings. She's too full of herself.
Example: Mary is very unpopular because she's so full of herself. She doesn't care about other people's feelings. She's too full of herself.