Performance

So I've been practicing 2-3 leetcode questions a day for the past 2 months and have gotten pretty comfortable at them. Problem is whenever I am actually taking the assessment for internships, I freeze and I end up having to google really simple stuff I can normally do. So far I had bombed 3 online assessments pretty hard (like passing 0-2 out of 10 test cases). After calming down, I go back, re-attempt them, and manage to finish them in under the allotted time. I can finish most leetcode medium questions in 30 minutes and some leetcode hard questions if I have seen the problem before. If I have to talk to an interviewer while coding, I start developing a stutter/can't think of anything to say and if it's just a timed hackerrank question, I end up staring at the timer longer than I should. I've tried meditating before the assessment, but as soon as I finish reading the problem, my mind starts racing. Funny thing is, I don't usually experience this problem in other high stress situations like test taking or sports. I just can't get comfortable during the assessments and interviews themselves. Does anyone else have this problem? Or have any tips on how to get better at the interviewing process?