It sounds like there were a number of issues with your return. If you are discussing forming an S-corp then it sounds like you are in the business of being a performing artist rather than being an employee who is a performing artist with a W-2 who is eligible to deduct work-related expenses under this special rule.
You may have an accuracy related guarantee claim, which someone else has already shared some information regarding, but for the upcoming year it sounds like you need to hire a professional tax preparer.
If you are not an employee you should never have been deducting those expenses at all in that area and they should have been fully deductible on your Schedule C. If they were in both places - then that is likely your audit trigger.
Also, this is based on AGI, but entering your income first doesn't automatically tell TurboTax what your AGI will be since many other entries can influence that number.
