My memory sucks... and I wanna be a history teacher :(

Hi, i'm 18 years old, and in the past year I gave the test that's necesary to enter any university in my country. To sum up: to study History at the best university in my city i needed 650 points and i got 639. Now i took a whole year of break so I can reach the necesary score easily. But now i'm concerned about my capabilities because when i'm studying I easily forget things that I'm supposed to already learnt like dates, definitions of some ideologies, events and their importance and things like that. So I would really appreciate some guidance or advice, maybe i should try another carreer related with history idk. I really enjoy reading this reddit and books about world wars, native history; and I believe that I MUST do something that i like for the rest of my life. Thanks for reading beforehands and my apologies for the bad grammar