Stuck in the Highlands

I've been trying to continue tracing my  McGregor line back, but have been stuck for quite a long time.  I do know that my 2x gr grandfather Alexander McGregor was married in Kingussie, Inverness in 1864 and was in Ontario in 1865 when their first child was born. Alex was born in Alvie in 1840 to John McGregor and Janet Meldrum.  Not married. I found Janet on the 1841 census still living in Alvie with little Alexander, her sister and their parents. Also on the census was 10 year old John McDonald, who is Janet's son. He came to Canada with Alex and his wife Elizabeth (Kennedy). Found no record here of John McD ever getting married.

I have not been able to trace John McGregor. According to Alex's birth record, John was a tailor, and had previously lived in Miltown, Dalraddy. Going on a hunch that he was about the same age as Janet, I started looking on the census records in Inverness-shire for a John McGregor born around 1810, who was also a tailor.  I did find one in Inverness, John MacGregor (close enough) but married with a family.  Same guy? Who knows. Might explain why he didn't marry Janet. Then again, Janet didn't marry the father of her first child. 

Totally stumped as to where to go next to find John and continue going back in time.  Anyone have any suggestions?

Thanks

Nanci