Can i use pvt.ltd with my firms name without registering it under ROC?

I commenced a small business of distribution of soft drinks in partnership, being inexperienced and by misguidance we kept our firms name as "Maa Narmada Pvt. Ltd" without registering it with ROC, though i got it registered with sale tax and even got a TIN no., so can i use pvt.ltd with my firms name without registering it with ROC, or i have to get it amend.