Self-employment tax question

I made $3230.40 on a 1099-NEC as an independent contractor working as an emergency physician and paid $915 in estimated taxes.  I entered this into TurboTax Deluxe and under the "Self-Employment Tax" section, it calculates my self-employment taxes as only $87.  It doesn't allow me to adjust it.  This seems low because I thought self-employment tax rate is around 15.3% so it should be closer to $490.  Thanks in advance for your help!

 

-Steve