thank you, i do intent to do it through a course rather than ministry.
The 18 month guideline is only if you're getting your full M via a course again, like you did for your M2.
For the MTO road tests the wait time is actually 22 months.
I think the 18-month rule applies even if you skip the M course. I did my M1 Exit at Learning Curves in late October 2013 and did the full-M test at the MTO in late June 2015. Counting on my fingers, that's less than 22 months.
How long did you have your M1 for? Perhaps the 22 months starts at the time you get your M1, so if you got your M1 in April/May 2013 then the math works out.
Alternately, did they let you take the exit test but not actually grant the full M on your licence until you were eligible, similar to the M1X? Lots of people go for the M1X course before the minimum 90 day M1 window, pass the course, but then can't/don't actually get the new M2 endorsement on their licence until the 90 days have passed.