Yes I have an idea of what you are experiencing having experienced something similar rather a long time ago.
I can definitely tell you that the feelings you will have on mdma are nothing like those induced by cannabis. You will not get the feeling that oh shit it's all turning weird on me again. You will not have the feeling that you need to keep checking that you're okay.
The only part of the mdma experience that can be a little stressful, especially for inexperienced users is the initial "come up" or rush.
You may suddenly be aware that your heart is beating hard, that something's happening.
I think it's always better for new users to have a buddy with them who can reassure them during that first half hour. You may also feel nauseous.
The panicky feeling at the start soon passes though and you will suddenly be aware that you feel good, that you are happy to be where you are, with the people your with.
If you have a decent meal about 4 hours before you roll you are less likely to feel nauseous.
I often feel cold and shivery as the roll is beginning. So it helps if the room is warm.
Finally I can also tell you that I can enjoy cannabis on the comedown from the roll, even though cannabis alone still provokes panic attacks.
Hope this answers your questions.
