real mj (as opposed to all the newfangled synth chemicals you kidz are so fond of) is a complex material that includes substances with both depressive and stimulating effects.
i believe, most people tend to experience it one way or the other--(1) some people say pot puts them to sleep, while (2) other people it makes want to get up and go paint pictures, see movies, and go shopping. (both groups get hungry, lol).
really, this is about as black-and-white a description of people as i know in the world.
i find it is exclusively members of group (2) for whom mj seriously potentiates mdma. you sound like a group (1) person. in general, pot is not even a favorite drug for (many, but not all) type (1) people.
i think the stimulation is what extends the roll, so if pot doesn't work for you, look for something else that's an effective but mild stimulant for you?