Don't be too worried.
For one thing, it will take some time for your application to be processed, even after you get allocated to a CO, and your ITA hasn't even gone in yet. So it may well be that by the time the CO is thinking about granting your Residence visa, you will have been living together for 12 months, or very nearly. REMEMBER TO KEEP COLLECTING EVIDENCE THAT YOU ARE LIVING TOGETHER.
No, the marriage certificate and bank account are not enough. Here
http://www.immigration.govt.nz/migra...artnership.htm is INZ's list of suggested evidence. And here
https://www.google.co.uk/#q=site:enz...tnership+proof are a lot of old threads on the forum, where this matter is discussed, which may well give you some ideas of what to get together. The basic idea is to prove the start of when you are together in one home - for instance, with a rental agreement in both your names, or mail coming through the post to each of you, at that same new address. Then try to have evidence that you are both still there (or together, if you are travelling), say three pieces of evidence of all different sorts, covering every passing week.
Keep collecting evidence all the time, while your application is being processed. It is completely normal for the CO to ask for more partnership proof right at the end, just before the visa is granted. This way, INZ are making sure that they don't issue a visa to someone who is not living with their partner any more.
If it happens that the CO finishes your case before you have 12 months' proof, it doesn't matter - this is covered in the rules.
http://www.immigration.govt.nz/opsmanual/30883.htm