Not quite two years. They're the closest in age of Ofsmuggar's kids -- Mackynzie was born in October 2009 and Michael in June 2011. There was also an alleged miscarriage (probably more like a late period) between them.
Since Michael, Ofsmuggar has had babies roughly two years apart -- Marcus in June 2013, Meredith (I always want to say Mereditz, and that's just wrong) in July 2015, and Mason in September 2017. I wonder if there was another miscarriage after Meredith, or if something else delayed the inevitable M5.