In CA, 18 years is the age of consent. That means that before a child turns 18, they're not capable to consenting to sexual conduct. It doesn't matter that it's consenual and that the underage one is the boy, or how long you've been seeing him, sex with a minor is still illegal, because of the lack of capacity for consent..
The parents (or teachers or clergy or neighbor) can't "press charges," only a state DA or federal ADA can do that, but they can all report this crime (yes, unlawful sexual intercourse with a minor is a crime), in fact they are REQUIRED to report it, and the law enforcement officials can prosecute if they see fit.
You need to see a criminal lawyer immediately.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
"Dating" isn't against the law unless you're encouraging him to stay out past curfew, break the law, skip school, etc. where it could be considered contributing to the delinquency of a minor.
Where the problem comes in is any sexual conduct (not just intercourse - any sexual acts) with a person under 18, even if they're a willing partner, is against the law. You could be looking at at something as simple as misdemeanor unlawful sexual intercourse (sometimes called statutory rape) if your age difference is under 3 years or a felony if it's more than 3 years.
You could also face other felony charges for any other conduct you can imagine.
Can the parents "press charges"? No. They can certainly report you to the police who can investigate and then forward their investigation to the DA for the filing of criminal charges.
The concerning thing is.... if they can trace back sexual activity to before he turned 14, then you could face child molestation charges and could be looking at sex offender registration for the rest of your life.
I'd strongly suggest calling it quits with him and consulting with a criminal defense attorney so you're prepared if charges are in fact filed. In the mean time, don't discuss this with anyone except that attorney in a confidential setting. Any admissions you make can only come back to haunt you.
I agree completely with the accuracy of the above answer. That said, "dating" him is not a crime. The crime would occur if you had contact of a sexual nature with him.