Medical costs are not reported on Schedule C. They are a personal expense, not a business expense. They are reported on Schedule A as an itemized deduction. They are deductible to the extent they exceed 7.5% of your adjusted gross income, and you have to itemize (as opposed to taking the standard deduction) in order to take the medical deduction.
Only health benefits you pay for employees go directly on schedule C. Your personal medical insurance can be an adjustment to income on schedule 1. But just the insurance. Everything else goes on Schedule A.
How to enter in the Desktop Home & Business version
https://ttlc.intuit.com/community/entering-importing/help/where-do-i-enter-my-health-insurance-premiums-in-turbotax-cd-download-home-business-if-i-m-self/00/26387
Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 17 as long as the expense is not greater than your net self-employment income. If it does exceed your net self-employment income it gets split automatically. An amount equal to your net self-employment income goes on Form 1040 Sch 1 and the remainder gets added in to medical expenses on Schedule A.
BUT do not enter any Health Care Marketplace insurance you bought. If you enter the 1095-A and select the "Self-employed and bought a Marketplace plan" box, it will automatically include those premiums in the SE Health Insurance section. So you shouldn't enter it again on schedule C.