My DD2 is almost 14 mo and we are still on two bottles (cow's milk) per day. She also happily drinks water and milk from a sippy other times. Lots of LO's really like the comfort of that bedtime bottle. When she takes her bottles, I hold them for her, and she is all business and drinks them quickly. So, I am really in no hurry to quit b/c as far as I am concerned taking 2 minutes to suck milk from a 6 oz bottle is no worse than drinking it from a sippy.
Having said that, I am planning on dropping the bottles next week after I return from a trip. I guess what I am saying to you is don't feel bad. Getting it down to only 1 bottle with a 12 mo is right on track, IMO.