The number of dives you have isn't that bad, but it depends on what kind of diving you've been doing, and your personal comfort level. If you've been doing caribeean reef dives in recreational gear, then you may not be ready. If you have been doing dives in low visibility, deep dives, wreck dives in more technical gear, 150 dives may be plenty. It also depends a lot on your comfort level with the mechanics of your gear. I suspect you've been diving in the St Lawerence river, since you are in Ontario, which does present it's own challenges.
If I were you, I'd enroll in a tech course. TDI's advanced nitrox, decompression procedures, and extended range courses are probably the best, but IANTD and DSAT also offer equivalent courses. You'll have to find what your local shops offer.
After that, you'll want to get into semi closed circuit rebreathers, such as the Dräger Dolphin. Each rebreather is specific and you have to take a course to be certified in each one of them. I'd recommend at least 100 dives on a semi CCR before you go onto a truly CCR.
Good luck.
Anyone who posts starting with a draegar dolphin should be immediately disregarded. Lol