I think it can be habit forming. Not really "addictive", but it is something that if you have a good experience on it you will want to do it again, and again.
You should probably fight this urge to dose often, a bit as taking it too much could interfear with your normal life and it will ruin the "magic" a bit.
I know how you feel though, I went through 250mg 2c-e by myself in 3 months which was less than half the amount of time I planned on. I'm taking a break for a couple months before I even buy anything else. I feel like having so many powerful experiences that close together has made me a bit more "kooky" than I should be. I actually like the aftereffects, they make me feel more creative, but that said, there is a limit on how much of this aftereffect I could weather before it starts becoming a burden. I don't know for sure but I think if I had kept it up for another 3 months at that intensity, I would be a bit removed from reality. The after effects wear off with time as you process the trips you had. I think once a month is a good schedule for 2c-e. More than that and you may start to feel lingering effects.
Hope my experience helps.