What are you using to smoke with? If you haven't tried already, I strongly suggest trying the Glass Vapor Genie. It seems odd to me that you can't break through on such high doses :S Are you getting all of it into your lungs in one breath? Practise makes perfect my friend

Glad it's helping with those pesky head aches though, I used to suffer from migraines as a child / teen and can fully empathise with how debilitating such things can be.
Best of luck on your quest for a breakthrough

Lose Control, Free My Soul, Break Me Open, Make Me Whole."DMT kicked my balls off" - od3