Dorian mode of C. See the modes tutorial on my website:

http://www.campin.me.uk

It could equally well be minor, it doesn't seem to make much difference of the A is flat or not.

Sounds to me like you really mean it to be in 6/8. It's very like the Gaelic song "I see the deer in the mountain pass", which is in that tutorial among the minor-mode tunes.