What kind of contraception did you take? There are two main kinds- the birth control pill and the emergency contraception pills.
A regular birth control pill is usually a small amount of hormone such as estrogen or progesterone that will help regulate and prevent pregnancy. However, this form needs to be taken every day around the same time and at least 3 weeks before it's at least 96% effective at preventing pregnancy. If this is the type of pill you took and haven't been taking it as prescribed then there is a chance you could be pregnant.
An emergency contraception is essentially a very large amount of the birth control kind of hormones. Taken within the first 72 hours after unprotected sex this is extremely effective at preventing pregnancy. However the sooner the better- so if it's taken immediately after an opps moment it's better at preventing pregnancy then it is if it is taken on the 3rd day. Because this is such a large dose of hormones it can have many side effects. Personally I had extreme nausea, cramps, headaches, and sore breasts for the first 3 days then had a small period 1.5 week early followed by very heavy one 2.5 weeks later. It can also cause bloating, vomiting, dizziness, fatigue, and irritability. Also it's not impossible for it to delay your period. Not everyone feels this- I was just one of the lucky ones who experienced so many side effects. However, that brings me to my next point- these are large doses of hormones and really shouldn't be taken more than 2x a year. They are for those mistake moments but not a regular habit.
If you took an emergency contraception, honestly all bets are off. You might have your period tomorrow, you might have it a week late. Take a pregnancy test in about 3 weeks if you haven't had a period. And don't be too afraid or surprised by any of the symptoms I described. Unless they're really really bad, it's considered normal.