I have an LLC, for which I sell through Shopify. This is business income, however, I get no 1099K. Should I just indicate this income as "other self-employed income"?

Yes, the income is self-employment income and will be reported on your Schedule C.  The IRS considers self-employment income as a business, so you will also be able to deduct common business expenses from your income. To enter your business and self-employment income, refer to the TurboTax  Help article How do I report income from self-employment?

Review the TurboTax articles Reporting Self-Employment Business Income and Deductions and What self-employed expenses can I deduct? for more information on business deductions.