@SecondPull,
Very wise words, thanks. And about your question the trip was very good. I'd certainly do it again if it didn't, well, fuck me. The first effect I noticed was strong lights at +1h, followed by things changing shape and form, the big kaleidoscopic hologram that covered my sight and things breathing very hard at about +2h. Lots of details and patters everywhere and a strong sensation of wellbeing. Cool parts included listening to music, playing videogames, watching psychodelic-vortex videos, talking to and playing soccer with friends, exploring the world and - one of the most epic memories of my life - riding a bike full speed when a monstrous rain fell down - that was just EPIC. FREAKING EPIC. Things started to turn out when I noticed the trip was lasting longer than expected. At +15h I could still see remains of the big kaleidoscope. I panicked.
Ok, now we're getting to the bottom of things. A panic experience on a psychedelic drug is orders of magnitude more intense than one while sober. When I had a panic attack on LSD+MDMA, I decided I was either schizophrenic or consensus reality as I had previously known it did not exist.
Afterwards, I had some PTSD-ey symptoms (not really diagnosable, and I don't think you are either, so don't get carried away and start looking up treatments...it's not really appropriate for your situation). But you did experience a trauma, and what's worse, it was kind of self-inflicted, so it's hard to get away from it. That, IMO, is the root of your current anxiety.
So what to do about it? Here is something that helped me:
when you start bugging out, don't run away from it. Find where the anxiety is physically located in your body. A lot of people carry it as a tightness in their chest, maybe in your neck, maybe your stomach, whatever. There's a physical response associated with the anxiety, and you should try to find out where it's located.
Now, think for a minute about what that anxiety is made of. There's this physical feeling, right? And then there's a STORY you're telling yourself about it. It might be "LSD fucked me, my life is over," or "I'm mentally ill/brain damaged" or whatever. Doesn't really matter, because it's just a story you're telling yourself. Let go of the story, and all you're left with is an uncomfortable physical feeling. Try to sit with that feeling, relax into it, don't hide from it, and the troubles you are experiencing will vanish. When the anxiety returns, just repeat.
Remember, you are just telling yourself stories. Without the story, the feeling has no power over you.