Did you save a copy (likely in PDF format) of your return when you filed? The amount you claimed in donations can be found on form Schedule 9. The form won't list individual amounts, but the total amount on line one of your Schedule 9 might help you figure out if you included the amount you're wondering about or not. In theory, you could check if you filed a schedule 9 for any of the tax years you're interested in.
If you used an online edition of TurboTax in 2016 or 2015, just sign into your return and navigate to the donations section of your return to see what you entered.
To navigate to the donations section:
- Open your return
- Select Find in the upper right corner
- Type Donations and select Go.