First and foremost, I'm no health professional so I just can give you my point of view.
Quote from: Sleandre
At 18 yo, I took ecstasy alone for the for the first time. It changed my life. When I was high, I felt like I could really embrace my feminity without the guilt. I felt like I finally understand who I really was, a woman.
This is very interesting. For one side, MDMA (ecstasy) is a pretty powerful drug with remarkable empathogen effects. It realeases a bunch of dopamine (euphoria, motivation, talkativeness), norepinephrine (energy, alertness, clarity) and serotonin (well being, peacefullnes, empathy). Its like being "high" in all possible ways at the same time, something similar to "pure joy" (thats why they name it ecstasy).
So while under its effects things may look clearer and you may feel at peace with yourself (egosyntonically) its just temporary. As stated by some professionals it may be useful as a tool to give you insight on things that sit really deep down, but is just temporary so therapy and further work may be done if you're looking to really work out things on a long term. Not to say it's just such an "extreme" conciousness state that can't last for long without doing harm.
Quote from: Sleandre
embrace my feminity without the guilt
This is a pretty important thing. There's a significant issue here: you feel guilty because you just happen to enjoy a sexual fantasy or certain activities not necessarily related to sex like crossdressing.
This looks pretty much like the process that takes place in OC (obssessive-compulsive) behaviours. You got an urge/thought/feeling that causes you distress, then you go for a ritual that alleviates it, but as soon as you finish, distress appears again. In away similar to what happens with drug abuse, too.
Quote from: Sleandre
I don't want to relapse again and go back to those bad habits.
I think it will be pretty good to first work on your guilt feelings. Self-acceptance is key for well being. Most people got kinks, fantasies, whatever you name it. They are just things you enjoy, it comes with your nature (just as liking food) and you shouldn't feel bad about them.
That doesn't mean you're transgender or you'd need to transition. Transitioning is much more than just trying to relieve guilt.
I think first step should be going to therapy to learn to accept your feelings, your desires, your likings, without being guilty, without thinking in terms of "who you are". Then, things may turn way more clear for you. And you'll be happier and healthier tho.