Since you applied by yourself and didn't entrust a patent agency, you will encounter some professional problems in both procedures and documents, and you need to spend more time to solve them yourself, so the authorization time will be extended.
At present, the authorization of utility model patents in China is generally about 1 year from the date of application. If it needs to be corrected many times, the time will be extended. Two and a half years without authorization is normal. The patent law does not stipulate the time limit for examination, that is to say, even if it is delayed for a long time, they have no legal responsibility. You can't sue them for this reason.
Whether your final revision is accepted directly affects whether the patent can be granted. I suggest going to the patent office to consult the progress.
If the patent application is rejected, it must be re-examined within three months. Review fee, 300 yuan. Submit the review request and modify the document. The Patent Reexamination Board will conduct a series of reviews on your patent application, and finally decide whether to accept the examiner's conclusions. If the re-examination committee thinks that your invention may be authorized, the examiner should re-examine it and make a conclusion again. If the audit fails, it is not too late to go to court.