Worrying about your design will make you better.   You will be better able to prioritize which part of the project needs more attention and hopefully this worry comes prior to construction so it can be corrected if needed.  James Gorden in his book Structures writes:

When you have got as far as working drawings, if the structure you propose to have made is an important one, the next thing to do, and a very right and proper thing, is to worry about it like blazes...it is confidence that causes accidents and worry that prevents them."  [Gorden]

In Henry Petroski's book Remaking the World, he states:

Many engineers see to have spent so many sleepless nights while their designs were progressing from the back of an envelope through increasingly complex nd detailed calculations anddrawings to the realization in an artifact upon whose safety the lives of so many depend.  If engineers do sleep, it is often with a pad and pencil nearby.  They are there to record not dreams, but nightmares, nightmares about collapses and explosions to be checked upon waking against the realty of a design.  And it is a good thing, for otherwise there might be more tragedies than we can imagine." [Petroski: 1997, 68]