Heart palpitations more relative at night.. and probably from my worrying about it. 22 years old ekg, stress test, holter all good, costondritis aswel?

You're right: You are young and work-ups have been done to assure you you have no heart problem. You are worrying yourself to death. Occupy yourself with things to do, things your really enjoy and I am sure you will feel much better. Sometimes solitude and too much free time can make us feel everything that can be wrong. Correct both and you'll live a healthier life.