Whoa...Congratulations, and you're close to my mirror image (not to mention I lived in Fort Mac a short while in 1979, and been in Calgary several times). I got certified age 51 (2005) and reached #500 in a little over 9 years. Am a few months away from halfway to the next (and last for me) big number. I started slow back then (30-50 a year) but got it up to 60-80.
A little tongue and cheek:
Remember what everyone on Scubaboard says--"It's not how skillful you are, how many cards you've collected, that you have varied experience in different locales, that your buoyancy is "perfect", etc.....It's how many total dives you have!!!
Slow and easy like us turtles wins. And remember, above all, it's a race!
Back to serious-- As you said, Calgary is a long way from the BC coast. With so few lake dives and fly out trips, how did you work it so most of the 500 were via shore trips? I assume that those 4-6 15 hour trips yearly meant staying somewhere and doing a lot of dives over a week or so?