Your question is a tad confusing as I believe you may have received some mis-information regarding appeals from criminal convictions.
A person convicted of a felony offense can appeal the conviction even if he/she received probation. HOWEVER, the notice of appeal MUST be filed with the court during the first 60 days after your sentencing hearing. So, if you have been on probation now for 18 months, you have long passed the statutory deadline to file a notice of appeal to challenge your felony conviction.
Now, if what you want to do is to reduce your felony offense to a misdemeanor, you can still do that. Once you have successfully completed the terms of your probation, you can file a motion with the court to reduce your felony offense to a misdemeanor (Penal Code section 17(b)). Once the offense is reduced to a misdemeanor, you can then move to have the conviction expunged.
You state that you are from Loma Linda and therefore I am presuming that you were convicted in the San Bernardino County Superior Court. This court has a great information packet on how to petition the court to reduce your offense or to dismiss your case after finishing probation. The information packet can be found here: http://www.co.san-bernardino.ca.us/Courts/pdfs/misc/FilingPetitionForDismissal.pdf
There are many criminal defense attorneys in the area who would be able to assist you with this process. I highly recommend hiring an experienced criminal defense attorney to make the process as smooth as possible.
Amanda F. Benedict
Law Office of Amanda F. Benedict
Appeals & Bicycle Accident Litigation
162 S. Rancho Santa Fe Rd., Suite F-20
Encinitas, CA 92024
(760) 942-0054 - phone
(760) 942-0055 - fax
Web Site: www.amandabenedict.com
PRIVILEGED AND CONFIDENTIAL COMMUNICATION
I think (and I only THINK this, I don't KNOW it) that what you actually want to do is move to have a felony reduced to a misdemeanor -- and, perhaps, to have your probation terminated early, which you can do after you've served half your probationary term, which you have. You can do both of these in the same petition, which you file using a Judicial Counsel Form CR-180. You can do this yourself, actually, although your attorney will probably have a better shot at succeeding. Here's the link:
There's a $60 fee, payable to the clerk of the applicable court. If you do it yourself, be sure to serve the prosecutor, and to add a certificate of service to the form you file with the court.
It sounds to me as though the judge has already told you he's not going to consider it this time, so my advice would be to wait at least that six months you talked about before trying again. Good luck.