I'm going through the same thing. It could be that we aren't smoking the BEST shit out there. And by the best, i mean the best. I don't smoke bad weed.
It could be the weed or like you said, tolerance.

The thing about weed is if you take a break. You'll get it back. Garunteed.

It's the everyday smoke that does that. Some say it's not smart.

I'm looking to invest in a Vaporizer.