Thank you for your medical query at AskTheDoctor.com
I understand your concern.
If you're positive that you pulled out you should not worry. A girl is allowed to worry as if something goes wrong she has to go through unnecessary pregnancy. Precum does not cause pregnancy, at least studies has not been able to demonstrate any viable semen in precum.
So wait for her period to come. Once she starts her period, she will be relieved of the mental stress.
Hope this was helpful,
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