Legal Question in Discrimination Law in California

You are mistaken. If you mean sexual relations, there is no difference between being 17 and 18, it is still statutory rape, and if you are having sexual relations now you are both guilty now. The only difference is that once you are 18, she will not be guilty of statutory rape too. (Yes, it goes both ways, younger and older, male and female, if your partner is under 18 you are guilty no matter how old you are or your gender unless you were physically raped). Parents cannot consent to their children being statutorily raped. They can consent to a minor's marriage. I believe the minimum age for that is 16. That is the only way to make sex with a minor legal. If you only mean romantic relations but not sexual, then you are also wrong. Non-sexual romantic relations are perfectly legal between an adult and a minor as long as no other violations occur, such as contributing to the delinquency of a minor or child endangerment or something like that.

Assuming your question is about statutory rape, the statute in California is Penal Code section 261.5. It is full of references to the age of the participants, and their ages and the difference in age between them may have a major effect upon the seriousness of the offense.

(I assume) you are committing statutory rape under PC 261.5(a). If you are within three years of the girl in age, it is a misdemeanor, PC 261.5(b). If she is more than three years younger, it can be charged as either a misdemeanor or a felony, PC 261.5(c). Section 261.5(d) does not apply.

When you turn 18, you will be an adult, and liable for civil penalties as well as criminal. Penal Code section 261.5(e) adds civil liability for adults, and larger ones for adults over 21.

It looks to me as though turning 18 will make your offense somewhat "worse" in the sense that you could be liable for a civil penalty (fine) as well as jail time, but you are subjest to jail time as it is.