If I only have a 1099-R form instead because I am retired. Am I only being taxed on my investment income??

If you only have a 1099-R form because you are retired, you are being taxed on the distributions from your retirement accounts, such as pensions, annuities, IRAs, and other similar plans. These distributions are typically taxed as ordinary income.

To enter your 1099-R in TurboTax follow steps here.  TurboTax will guide you and help determine what the taxable amount is.