You might be doing the worksheet by hand wrong. It can be tricky.
To see the Social Security Benefits Calculation Worksheet in Turbo Tax Online version you would have to save your return with all the worksheets to your computer. Or if you are using the Desktop CD/Download Software you can switch to Forms Mode (click Forms in the upper right) and click on SS in the list on the left side.
Is your Social Security taxable?
https://ttlc.intuit.com/community/income/help/is-my-social-security-income-taxable/00/25600
IRS Pub. 915 on Social Security. There is a worksheet on page 7.
https://www.irs.gov/pub/irs-pdf/p915.pdf
