This means your CEP isn't high. Most likely, that's why your SL and RO did not tell you the truth. CEP is confidential. Only your SLs and ROs will know.

Masters degree does not really have much effect on rate of promotion. But the class of honours do have an impact on your starting pay. That's why for teachers who subsequently upgraded and did a masters, they didn't see an increment on their pay.

Likewise for BTs who entered service without work experience, their starting pay is based on their classification of honours, even if they have a masters degree. Hard truth but that's a fact.

I have seen my fair share of teachers who despite being emplaced on the old GEO2.1 scheme were promoted multiple times.. It has got to do with their performance and CEP.. Their performance grades have been consistent Bs. You mentioned your performance is all C. That explains also. One teacher who despite being emplaced on the old geo 2.1 scheme has already hit GEO 5 within 7 years in service.

Hope it helps.