iPhone Calendar. Can only search one previous year

Ive been using iPhone calendar for as long as Ive had an iPhone (since the beginning). When I search for things from prior years like anniversaries or weddings or vacations, nothing appears. Why cant I search my calendar since inception? Ive been recording things in my calendar thinking I can refer back and I can’t. Very bad for someone like me I have a horrible memory and I want to be able to look back. It’s almost like my diary was deleted! How do I fix this problem? It’s not my settings and Ive tried 3rd party apps but nothing works! Why should I need another app to access older data in the first place? PLEASE HELP!