I just filed my taxes using TurboTax, but I'm an international student and I don't know if I was ever given the option to make that clear. Do I need to ammend my filing?

When did you first enter the US?

For the first time with this F-1 visa? 2013

Please see answer below

As an F-visa holder, you are considered as exempt (not counting days) for five years from the year you first enter.  In your situation, you are treated as a non-resident for 2013-2017 and required to file a Form 1040-NR. 

If you have already filed with TurboTax, to amend from Form 1040 to 1040NR,   please follow these steps:

(Please note that you should not try to amend your return until it has been fully processed and you have received your refund or your payment has cleared.)

As TurboTax does not support any nonresident tax forms, you are recommended to use our affiliated partner, Sprintax to complete your Form 1040-NR.

• Download Form 1040-X from the IRS website ( see below).  On the front page of Form 1040-X, enter your name, current address, and social security number (SSN) or IRS individual taxpayer identification number (ITIN)
• Do not enter any other information on page 1.  
• Do not complete Parts I or II on page 2 of Form 1040X.
• Enter in Part III the reason why you are filing Form 1040X.
• Complete a new Form 1040-NR by using Sprintax, see above.
• Across the top of the 1040-NR, write “Amended”
• Attach the new Form 1040NR to the back of Form 1040X

For more information, see:

https://www.irs.gov/pub/irs-pdf/f1040x.pdf  - form

https://www.irs.gov/pub/irs-pdf/i1040x.pdf  - instructions

page 5 under Residents and Nonresidents

Thank you, this was really helpful. Can I still submit the form electronically?

No, you can't unfortunately.  IRS does not accept amendment by e-file.