If your rental had a loss, that is a Passive Loss. However, because you "actively participated" in the rental and your total income was under $100,000, you are allowed to use up to $25,000 of Passive Loss on that tax return. Because your loss was under $25,000, you would NOT have a Passive Loss Carryover for those years, you would have a NOL (Line 41 of your Form 1040 will be negative) for each of those years.
As you say, the deadline for 2014 is not until next April. That means you can still amend your 2012 and 2013 tax returns for the NOL that occurred in 2014. The 2014 NOL is first carried to 2012. It would only go to 2013 if it was not used up in 2012. Your 2015 NOL would be carried to 2013.
