How do I do my taxes if I'm self employed and only get paid in cash?

You don't need a 1099-Misc to report your income.

HOW TO ENTER without a 1099-MIsc

 First, sign in to My TurboTax

Next, click the orange Take me to my return button

On the white bar at the top, click Federal Taxes

Then, Wages & Income

In the Self-Employment section (you may need to click Show more), next to Income and Expenses, click Start (or Revisit)

When asked "Did you have any self-employment income or expenses?" select Yes

You'll see the screen titled "Tell us the type of self-employment work you do." Enter your description, then Continue

On the next screen "Let's get income for [description]" select the button Additional income. Includes 1099-K, check/cash payments and Continue 

The next screen will say "Tell us about additional income for your [description] work." List descriptions and amounts on this screen

You report the income from your own records. The IRS considers undocumented cash income (no W-2 or 1099-MISC), for work performed, to be self employment income. Enter at "Business Income & Expenses" and TurboTax (TT) will complete Schedule C or C-EZ for you and allow you to deduct any expenses associated with this income. You'll also have to pay self employment tax (social security & medicare tax) on any profits greater than $400.