I have the Nixit and it's working great for me so far (only one cycle, but I have a very heavy flow). However, since the rim is not as firm, sometimes it also feels like I'm not tucking it up as far as possible behind the pubic bone. If you feel like you are pushing as far up as much as you can, the disc may just be the wrong size.

Thankfully it only autodumps when I'm bearing down for a bowel movement and I do have to tuck it back in. I wasn't even paying attention which way I was angling it for insertion, but I believe upwards towards tailbone is correct.

As a fellow Canadian, we do not have many options unfortunately. I saw somewhere else on here that you can purchase the Moonthlies disc on the American Amazon which can ship to a Canadian address. Each order comes with two, so you can try the set which has both sizes (you have the option of either 2 small, 2 large, or 1 of each). The rim seems to be firmer which might help you in tucking it upwards more securely.

Here is the Amazon link:

https://www.amazon.com/MOONTHLIES-Reusable-Menstrual-Disc-Alternative/dp/B09Y26PMD5

Edit: we don't have Cora or saalt or the hello disc available, but there are some white label brands of discs on the Canadian Amazon, like Pixie (it seems to be the same size as the Nixit but with a different shape so I don't know if you would want to try that... I'd recommend Moonthlies) there's also disposable ones but I'm assuming you want something reusable