Northern Ireland's population is set to pass 1.8 million at some point this year. But it hasn't grown 200,000 in 2 years or 12% as you state since 2009.
See here:
27 May 2010 - Population growth expected to be strongest in West and South of Northern Ireland | Northern Ireland Executive
Furthermore, the republics population hasn't declined. Recent sources have shown that the greatest migration occurred in 2009/2010 of in the region of 40k, yet with this factored with natural increase, the republics population had a net gain of circa 10k.
See here:
http://www.cso.ie/releasespublicatio...ent/popmig.pdf
So I'm correct in saying Ireland as a whole has a population around 6.3million. And if the economy gets back on track, and average growth resumes as experienced in Austria and Sweden in the past decade, I'd say I'll be 60-65 when the Islands population surpasses the pre-famine high.
*Sweden and Austria having experienced growth of around 300k+ in the past ten years.