You have missed the first opportunity for emergency contraception - the morning after pill which is effective up to a week (three days are recommended).
You can do a home pregnancy test right now. Get two, of different brands, and follow the instruction with the tests at least twelve hours apart. Your doctor or a women's clinic can do more sophisticated test but woul likely begin with the same test you can do at home.
The only "pill" is mifepristone (sometimes called RU-486) which is effective for a few months after conception. In some countries this can be had without prescription. In most countries, it must be administered by a doctor. It is actually multiple doses and very few women who have taken it look forward to repeating the experience.
You should see your doctor, or visit a women's clinic, as soon as possible to determine all of your alternatives at this point. The sooner, the better.
Posted: 30 Sep 17:48