Hun, I have to get some rest. Been up since 6 am, studying for an exam, fail with a grade of 79 and I am kicked out of school, and I have a very sick child.
Just don't have sex until you are ready for a lifetime commitment to the child and the boy who is the father of the child.
There is no birth control that is 100% effective except for abstinence. If you are not ready to be tied down to a baby and a boy, for the REST OF YOUR LIFE, you are not ready for sex.