What most candidates don't realize is, you can't actually study for "the test", you have to study the core material to have a basic understanding and knowledge of the concepts and methodology of treatment. People always say, "The test was nothing like what I studied." Right. It's not ... but none of the concepts and ideas on this test should be foreign to you.
A good test prep service, like JB Navigate, will identify areas where you are weak and provide rationale for the correct answers, so you not only learn to recognize the presentation and treatment of common EMS patients, but you'll understand the WHY behind it.
Saying you 'psyched yourself out' is a cop out. You either know the core concepts, or you don't. You failed the adaptive test so you're you're obviously weak in several areas.
And you saying medictests.com is a good website isn't exactly a glowing recommendation. What makes them good? Certainly not how they prepared you for a computer based adaptive test.
Study, learn and retake it.