First, a couple of notes. Please don't use the term "statutory rape." You're referring to California Penal Code 261.5, unlawful intercourse with a minor. Individuals like your dad don't "press charges." The District Attorney does and, unfortunately, once the cops and the DA get involved, it's out of your hands.
Because you're under 18, the law says you can't legally consent to having sex. Even if you said "yes," it's against the law, and your boyfriend, as the adult, is supposed to refrain from sex with minors.
In California, one defense is a reasonable, good faith belief that the "victim" is actually over 18. That can happen, for example, when someone meets a very mature-appearing 17 year old who got into a bar with a phony ID. Since underage people aren't supposed to be in a bar in the first place, it would probably be reasonable to believe the 17 year old was really an adult.
(NOTE: This defense applies in California, but is not recognized in all other states. It only applies to a belief the "victim" was over 18. "I thought she was 16" is not going to save you from being convicted of having illegal sex with a 13 year old, which is an even more serious felony.)
Of course, in your case, it probably wouldn't fly. You've been together with your boyfriend for a while and he probably knows how old you are.
If the prosecution serves you with a subpoena, you would have to go to court and testify or you could face arrest and jail. (For some sex offenses in California, they can't force you to testify, but this isn't one of them.) However, unless you're actually called to the witness stand, you are under no obligation to speak with anyone about the case, including the prosecution and police.
Finally, how the heck do the cops know you and your boyfriend had intercourse? That's pretty hard to prove unless you told them, somebody else saw you, or you had his child.