We know the feel when you work so hard and test scores do not match up to expectations. Given the fact,that you are a full time working professional, the efforts you have put in are COMMENDABLE!
Now to come back to the scene we believe the following pointers may help you:

(i)ANXIETY- Like you have mentioned,anxiety is a huge obstacle. Anxiety creeps in when we are under prepped or over! We suggest have a balanced prep where you have internalised the concepts and have a positive healthy attitude all during your prep journey. That said, we also understand that its easier said than done! Try making GMAT prep a habit/like a routine so that the anxiety part is controlled to an extent. Just before the GMAT have a thorough revision and focus and train yourself to be calm. [link to our video on that attached][/u]

[u]In fact, teaching/training yourself to stay calm can be or rather should be considered an integral part of your GMAT prep.

(ii)We also suggest to reverse work on yourself and subject yourself to the pressure of time during practice/mocks by reducing the time to perform.
Target a reduced time! That way, the original paper can be relatively easier on your brain when you encounter it. That said, this is a tricky scenario. If you find it exhausting or creating anxiety in any form,try training yourself to not feel it and yet perform. If the same persists, then we suggest go for practicing increased number of questions per day.
Either ways, expose yourself to performance prssure under such a simulated yet controlled atmosphere and teach your brain to stay calm and focussed during the prep.

(iii)Now,once the anxiety issue comes under training,make sure that you "internalise" the concepts by practicing through questions relevant to every concept. That way you should NEVER need to go back to videos once you have completed it.(bcz it stays all in your mind by the time you complete!)

(iv)Take mocks and analyze your errors.Make sure you train your thought process enough to NOT repeat a mistake if you have analyzed it once.

(v)Revise,Revise and Revise!! Have the formulaes ready. Have the verbal flashcards ready. And most of all,make sure you have it all in our brain emedded.

(vi)Strengthen your STRONG areas. Make sure you do not make a mistake in them. Infact,you can prepare topics in descending order of your strength in topics.

(vi)Complete your prep with at least a week at hand where you train yourself intensively to be focussed and calm.
Given the real dealbreaker being your nerve reaction to the paper than the ability(which we do not doubt, given the way you prepare even with a full time job!)

 (vii) Finally Shrujal, remember there is no do or die situation! Nothing in life is worth feeling "devasted" for.Prepare well,be confident and have a healthy,positive attitude throughout.If sometimes things do not work and life seems unfair, we have to figure out a solution and make the DEAL happen.Thats what you as a FUTURE CORPORATE is expected to do!