I have heard that weed from the 70s era only had ~2% THC where now at least dispensary grade can hit 20% to 25% THC. That could well be due to the drug war selecting for more powerful highs in smaller packages, but i would think that would also reduce the quantity needed to get the high you want.
I have the same thing. What I find works for me is to vape a little flower in addition to the edible. No idea why, but it’s somehow like vaping some ‘activates’ the edible.