My first experience was also an overall unpleasant one. One of the first intelligible things I said when I came out of it to my friends was "I don't think I need to do this again."
It's funny that it came about that way because when I first found out about DMT I thought I had found what I had been looking for since I was very very young. That yearning to find out something, something bigger than reality.
But after letting several months pass I think I'm where you are right now, but I'm more convinced to jump in again, BUT with a different outlook on it.
I can't tell you how many times I've seen "set and setting" on here, and it's true, it just has to be. Part of that set and setting though is you. You have to know your intentions with yourself, you should also know quite a bit about yourself as well since you've taken it once. I know that my experience showed me to familiarize myself with relaxing techniques, and that even though I have a solid frame that my mind and psyche sit on that I needed to gain a whole level of control of it.
There are many ways to gain more control. Meditation should definitely be something you look into.
If you're saying deep down at the core of you "i need to do this again" for whatever reason, then I think you should conquer yourself and in turn surrender to whatever is to come from it.
But if you're anything like me, giving advice is the easiest thing to do, but to take it is a whole other thing
Pick a good day, find a bit more of yourself, and then give in. Best to you