Your method, basically, sounds fine (except for not measuring with a meter how much CO you were producing, which is IMPORTANT). Yeah, the problem is with your SI. I don't mean to be disrespectful, but it sounds like you really don't want to die. You still have a bit of hope you're holding onto. And if it took you 10 minutes to feel like you were about to pass out, you weren't generating nearly enough CO with your setup, hence, the need for a good CO meter that is capable of measuring up to 10000 PPM concentrations. If you were generating enough CO (and waited long enough to reach above the 10000 PPM concentration in your enclosure [bathroom]), you would have been unconscious in mere seconds, like no more than 20 - 30 seconds. This is ideally what you want to have happen. Bathrooms aren't than small and will take some time to fill with CO. The smaller the enclosure, the better. That's why many use tents.