2000' too high with 50nm to run is ok, but not with 15 to run... Don't know where you were so can't comment. It's obvious to me your stress was stressing the captain, not much you can do as you'll see through your career you'll fly with pilots actually scared of flying! As others have said, watch others fly and learn from them, mentally fly the a/c with them and see what they do differently and why, judge from the outcome, even take notes of your own shortcomings and think about them doing chair flying, or trying things out on your pc with flight simulators.
Don't worry we've all been there, but as for me, I'm proud to say I learn every day from everyone I fly with
