If you traveled to Spain together, then that time counts towards your common-law qualifying. Any time spent in person together, counts towards qualifying time.
So you really need to confirm the specific month you reached 12 months of continuous cohabitation together, regardless of where in the world you happened to be living.
You indeed "officially" became common-law after 12 continuous months of living together. This is fact based, and based on Canadian law. It it not your decision if you can choose to become common-law, it simply happens based on the dates. So if you became common-law in 2012, but filed taxes as 2 single people, that is clear tax fraud.
Also if you submit old option C printouts for 2012 or 2013 and they clearly say single, but you are saying to CIC you were actually common-law... that may be a problem. You should really go back and re-do all your old taxes. You may need to pay back any benefits/credits you were getting that you weren't supposed to as a common-law couple, if applicable. You may need an accountant to do all this.