Based on what you have described, if your boyfriend had a condom on and he did not ejaculate inside your vagina, the chances of getting pregnant from that encounter are unlikely.
The only way to determine whether or not you are pregnant is to take a pregnancy test. Most home (or clinic) pregnancy tests will be accurate after you have missed your period. To learn more about pregnancy testing, click here.
Besides being pregnant, several things can cause you to miss your period. Some of these include:
- Birth control may cause a changes in periods including, not having one
- Certain medications can cause changes to your periods
- Some illnesses can change or delay your period
- Malnutrition and low body weight can cause problems with your periods
- Excessive exercise can disrupt your hormones and cause your period to stop
If you have concerns about your changes in your period, see your health care provider.