I had the same experience during my high school and college years. THC consumption (with alcohol or without) consistently induced anxiety (sometimes so much as to induce mini panic-attacks).

Fast-forward five or so years, and I gave it another shot out of curiosity. Interestingly enough, my experience was starkly different. I guess you could say I experienced the traditional side-effects that I had missed my first time around. What's most notable is the subtle after-glow I would feel days after using THC.

I have since been using THC while practicing mindfulness and the benefits have been enumerable! It's quite interesting what role age, set, setting, etc. can have during these experiences.