[Lizzie]

Hey, welcome to Teenhelp!

Using condoms alone (according to WebMD) protects against pregnancy around 82% of the time. So while you may have done everything right, there is still a chance of her getting pregnant.

Since it has been three weeks since you had sex, she can take an over the counter pregnancy test. These can be bought at any grocery store or pharmacy. It only takes two weeks from the day of having sex to get an accurate reading from a pregnancy test, so whatever the result is, it should be accurate. I highly recommend that she takes a test.

If she isn't pregnant, then I strongly urge that she get on a second form of birth control. Taking something, like the pill, along with using condoms is much more effective against preventing pregnancy than condoms alone. And remember that there is no form of protection that works 100%, there is always a chance of getting pregnant when having sex. Birth control methods make pregnancy less likely, but not impossible.

If she is pregnant she needs to see her doctor to get blood work done to medically confirm the pregnancy.

Feel free to let us know if you have any more questions.