Do not worry. It is very very unlikely that you are pregnant.
infact, stressing can actually delay your next period so just remain calm and keep living your life the way you would normally do. There sadly is not food that can prevent pregnancy but comfort food might help destress you
From personal experience, stressing over situations where that chances of pregnancy is highly unlikely can mess up your mind. So make sure you talk to your boyfriend about the importance of using a condom when you guys have sex for real but for now I think what youre doing/what you did is harmless.
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