It's not like getting pregnant is guaranteed or anything, it takes people a lot of trying to conceive, pregnancy tests are also used to see if you actually ARE pregnant and there are other things you can buy to help you tell when you would be most likely to conceive, etc. What you did was just a precaution. The morning after pill is just like taking some other contraceptive that makes stuff in you sterile.

The morning after pill:

"[The morning after pill] is believed to work principally by preventing your ovaries from releasing an egg, and by affecting the womb lining, so that a fertilised egg couldn't 'embed' itself there."

Birth control pill:

"Most birth control pills are "combination pills" containing a combination of the hormones estrogen and progesterone to prevent ovulation (the release of an egg during the monthly cycle). A woman cannot get pregnant if she doesn't ovulate because there is no egg to be fertilized. The Pill also works by thickening the mucus around the cervix, which makes it difficult for sperm to enter the uterus and reach any eggs that may have been released. The hormones in the Pill can also sometimes affect the lining of the uterus, making it difficult for an egg to attach to the wall of the uterus."

As you can see they pretty much perform the exact same function. There are many times where you could be trying to get pregnant and a fertilised egg couldn't embed itself on the uterine wall anyway so it's not like it's different than not getting pregnant normally. There are also cases where the fertilized egg cannot even pass into the uterus to begin with.

I know emotionally this all seems harsh, but in reality it's not like something evil transpired.