What makes me too young?

My girlfriend is 33 and I'm 29 and she's convinced im too young for her. We keep dating and staying with each other but she acts "above" me even though my education is superior to hers. She can't get over the 4 year age gap regardless of continued and dating. Is 4 years that drastic of a difference? Especially when I spent 5 of mine working as a special operations Marine and still finished school? her unemployed apathetic ex, who left her, �has convinced her otherwise. Please help me understand!