The trouble with drugs is that their effects and effectiveness can change dramatically from person to person. MDMA is no exception, and for this reason can be dangerous, and that's before even considering your preface; Street level drugs vary in purity and what they're cut with.
On the cut subject, it should be noted that many pills are cut with methamphetamine, depending on where you are in the world. The reason is because it creates a better high. The speed kicks in and gets you energetic, excitable and amped up, and the trip kicks in a little while later. In some places the amount of speed cut with the MDMA is actually a selling point. I don't think I need to point out why speed is dangerous.
Another thing OP is neglecting to mention is the come down, which gets progressively worse over time. Over time, most people find themselves popping more and more because the more you take the grander the high feels. By the time you're reaching 5-6 pills in a night, you're going to be having some pretty bad come downs the following day(s). You get scatterbrained, you can't get comfortable, you're extremely lethargic, and so on. It's like a nagging hangover without the headache. And it burns you out.
I hate to be that guy, but OP lacks experience. I popped for years, and I have a fucking great time doing it, but it would be a bold faced lie to pretend like there weren't downsides, and to pretend like it was pure, unadulterated, fun. There were risks. I just happened to fully understand what those risks were. Most people don't.
No amount of research can properly prepare you for your first high. It isn't like weed. Things don't just get fuzzy and giggly. Harder drugs alter your perception, change your sensory experience, often profoundly. A drug like MDMA is equally as likely to give a person with PTSD epiphany moments as it is to trigger panic and flashbacks.
OP, I'm glad you had fun and that you feel you've made some headway in getting better, but you're walking a dangerous line. I hope you understand that.