Is it weird that i want to wait til at least 21 before having in case i get pregnant before then..?

like i know people say wait until you're ready but my body is ready, it's the fear of pregnancy deters me..i'm 19, and i know if i got pregnant right now it would completetely screw up my life and my freedom, and ok by using the pill and a condom it's pretty unlikely but only takes one mistake and my freedom is gone forever..am i being unneccessarily cautious? just 18 years of responsibility seems like a huge price to pay for a few minutes of pleasure..