Preventing pregnancy naturally??

Hannah
Okay. I'm only 16 and I'm not even having sex until after marriage. 
However, the first time I ever have sex, I don't want a kid on the first time and I personally want to have sex naturally without any form of condoms or birth control. 
Isn't there a way to like know when to have sex without getting pregnant like when you're ovulating or fertile????
Clarification on the last sentence: 
For example is there a higher risk of pregnancy when you're ovulating, fertile, both, or neither?