Interesting question, but the answer is simpler than you might think.
Antibiotics put selective pressure on bacteria. Bacteria resistant to that antibiotic evolve as only the resistant ones survive. But this is the key, there has to be at least some already resistant bacteria from which the new (resistant) population will emerge.
With contraception, this is not the case. There are no spermatozoids capable of penetrating condoms, for example, and you should also bear in mind that in most cases mild hormonal disbalance is enough to prevent conception. It's a very delicate process, and contraception is basically an overkill.
Even if some spermatozoids could penetrate condoms, that trait would have to be hereditary in order for evolution to occur.
If you'd want to prove that contraception constitutes selective pressure on humans you'd first have to prove that there are spermatozoids and egg cells that can beat contraception, and that it's hereditary.
Evolution doesn't work the way you think it does. If you kill a random person, even if you kill a million people, it's not necessarily selective pressure. There are rules to evolution, and one of them is that it has to be hereditary.
This is not.
It wouldn't even come close to being artificial selection, let alone natural selection.
Besides, there's 7.3 billion of us. More than ever. We can hardly say contraception is reducing the world's population.
You also fail to see one thing, that a person who uses contraception in teenage years still has kids as a young adult. Contraception just delays pregnancy until you're ready. In evolution, there's a concept of "surviving long enough to reproduce". You can both use contraception and be an organism with 10 kids - though not at the same time.