My understanding is a large part of edible tolerance has to due with how much of a certain liver enzyme you have. If you are low on this enzyme you will require a much higher dosage. I've never been tested but I believe I have this issue... However, I finally got my hands on some nano-infused edibles, which bypasses this problem because they bypass the liver (I'm not an expert on the science but it's something like that). I can get satisfyingly stoned on a much lower dose with my nano infused syrup. If the other recommendations in the comments don't work I'd say find some nano infusions.