"My basis is $11k" and "All the money in this IRA is post tax" seem to be contradictory statements if you made an $50k distribution. With $11k of basis, no less than $39k of a $50k distribution will be taxable; more will be taxable if you have other money in traditional IRAs.
Your Form 1099-R is correct. You must enter it exactly as received. All of your traditional IRAs are considered to be a signal account for the purpose of determining the taxable amount of a distribution when you have basis in nondeductible contributions. TurboTax automatically prepares Form 8606 when you enter the Form 1099-R and after clicking the Continue button on the Your 1099-R Entries page you enter your basis and your year-end balance in traditional IRAs. The Form 8606 will be part of your printed tax return.
