Most traffic violations in CA are infractions. Penal Code § 19.7 says the limitation of actions for infractions is the same as that for misdemeanors. Therefore the charging authorities have one year to cite you for this violation.
Mr. Kaman is correct. So stop calling them to remind them that this citation is still outstanding. If you keep at them, I am sure they will find it and prosecute it.
I agree with Messrs. Kaman and Dinday.
However, make sure that the citation you were issued did not instruct you to go to court on a particular day or within a particular time period. If it did and you went to court, and once there were told that nothing had been filed, you should look for a "courtesy notice to appear" which will be sent to you by the court or the DA once it has been filed and a date set.
Don't want to alarm you, but what could happen (I see this all the time) is that the court will not sent the "courtesy" notice, your case will be called on a day about which you know nothing, and a bench warrant issued for your arrest. This is wrong, but unless you or your lawyer catches it, the court will get away with it. A bench warrant under these circumstances is wrong because a bench warrant implies that you (a) promised to appear (as signified by your signature or presence in court when ordered to appear) and (b) you violated your promise.
So, as was pointed out, you have one year until you can relax about this. I respectfully disagree that you should stop calling the court since they are not the agency/entity which does the filing. Don't get crazy and call once a week, but I would keep up with it.