Would wish this to be a one line response, but that's not the reality of your situation...
Checkitis is not unusual. Debilitating checkitis is rare, but we've seen it before, and it can be overcome... I have been giving checkrides for over 25 years, and have seen all levels of competency, and EVERY airman has a level of "checkitis"... The trick is to keep it from controlling YOU.
A little anxiety is good - it makes your situational awareness better, and keeps you sharp. Too much anxiety can be debilitating. The good news is that you create it and you can learn to effectively manage it. Anxiety is born of fear, and fear is an emotion, and it can be controlled by thinking your way through it...
Checkitis is a form of performance anxiety, and is manageable either by self awareness or counseling...
As for using self awareness, you need to KNOW and BELIEVE deep down that you
A) Have the skills
B) Have the knowledge
C) Have ALWAYS been able to do the job well
D) Have always SUCCEEDED eventually. (This is undeniable proof of your ABILITY to do the task)
To do this, you have to convince yourself that you KNOW what you need to do, just DO IT, and that success is normal. Some of this may sound like psychobabble to you, and you are free to use or ignore any of it:
Your mind is a great computer, but like a computer, it only does what it's told... We program our minds daily by how we interact with it... This is an outline for further study... you have a whole internet to scour for information:
Self talk can be your best friend or worst enemy..If you say to yourself "I can't do it"... guess what... you won't. If you say "I CAN do it", you open up the possibility of success. WHEN you are successful, that is another block in the wall of your competence. If you fail, consider it an OPPORTUNITY to learn how to SUCCEED rather than "another failure".... Beating up on yourself gets you.... NOWHERE. Providing yourself opportunities to succeed is liberating A positive mental attitude and positive self talk set you up for SUCCESS.
Visualization is one of the most powerful techniques used by world class athletes and flight demonstration teams, and that I use it to focus anxiety for positive outcome... Starting about three or four days before the checkride, using a Practical Test Standard, run through the PTS, and visualize doing each of the maneuvers PERFECTLY. Your instructor has signed you off, indicating that you possess the ability. Visualization reinforces the belief that you KNOW how to do the maneuver.
This response to your question is lengthy and complex, because the challenge is complex. Immerse yourself in digging out information on these topics... there are hundreds of articles on the web... A session with a counselor can provide other resources or ideas, or help direct your efforts.
As far as the airline interview is concerned, the only path you have is to successfully complete a course of "anxiety control" and explain the process you used to overcome it adequately.... One thing is certain, unless you make a positive move to manage your anxiety, your dreams of being an airline pilot are unlikely to be fulfilled.
EDIT - @JetMech - IMO, more flying practice can't hurt, but it's pretty expensive, and the issue is headwork, not hand skills... reprogramming the brain for success is the goal...