If abstinence was the answer, there wouldn't be teen pregnancy. And the birth control market would drop substancially. ;)
the simple truth is abstinence does not work. Mostly due to being 'caught up in the moment' issues. It is far better to be prepared than to think you just won't have sex anymore.
If you are using a copper iud and condoms you are more than protected. If you are still concerned, use some spermicide also. If you become pregnant with all of those methods, then perhaps that is what fate is. Perhaps, much like when we die, when it is your time, it is your time. If you've done everything to protect yourself and you still become pregnant, it would indeed be 'your time'.
However, if you add up the effectiveness of those combined methods of birth control, it would be over 100%, so that's pretty safe.