I agree with everybody here above me,... you needn't worry thàt much really...
If you'll take the pill correctly and consequently, it should be protective enough. I've taken the pill now for over a year and haven't gotten any problems yet. I do freak out sometimes too, you know... nothing is a 100%, except abstinence, but that is not worth it for me really
Maybe you should talk to your doctor about your worryings, and he/she might help you further.
Good lucks to ya!