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For the purposes of this answer, I am going to assume that neither of you live on a military base or federal government property.
The age of consent in Illinois is 17. There is no exception to parties who are close in age.
This means that if persons such as girlfriend and you engage in sexual activity before you turn 17, she can get into serious criminal trouble. It would be best to wait until all parties are at least 17 or older.
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