You seem to lack a grounding in basic logic. What I have is an equivalence (several items which do the same thing — i.e. modify the natural functioning of the body for the convenience of the owner), not an analogy.
Here’s why your analogy, or whatever you call it, doesn’t work:
If you take a hunger-canceling pill (contracepted intercourse) when a dinner (natural intercourse) is available to you, you are engaging in self destructive behavior, which is immoral.
If you use contraception (sugar pill) when you are unable to conceive anyway (no dinner), it is no big deal, other than it is stupid.