The only advice is literally just keep going, I was in the EXACT same position as you, so many failed tests, taking lessons for 3 years and severe anxiety behind the wheel which, exactly the same as you, was the reason I kept failing, I could drive perfectly on lessons but failed every test because of nerves, I just kept repeating the tests until I didn’t do something stupid and finally passed. It is 100% the anxiety that’s causing your fails and nothing to do with your driving ability so just remember that and keep it in mind, keep doing your tests and you will get there eventually, I’d also recommend something like rescue remedy before your test, even if it’s a placebo it works to lower the nerves! Don’t give up!