There's always a chance. Plan B is not guaranteed to work. It's pretty effective, though. It could make you have irregular bleeding, so the early bleeding you noted could be from that.
If you are going to be regularly sexually active, you might want to consider something more reliable. And if you do plan to continue just using condoms, ALWAYS use spermicidal cream or jelly with the condom.
If you only use a condom and it breaks, you can also insert an applicator ful of the spermicidal cream, jelly, or foam immediately after intercourse (so it's good to have on hand all the time anyway). This will help furthur, but you'd still need Plan B.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.