Self-employed health insurance deduction goes on Form 1040 Schedule 1 line 16, as long as the expense is not greater than your self-employment Schedule C Net Profit minus the deductible part of the SE tax (from Schedule 1 line 14) and any business retirement plan contributions on line 15.
Then schedule 1 line 22 Adjustments to Income goes to 1040 line 8a.
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 Schedule 1, and the remainder gets added in to medical expenses on Schedule A.
self-employment income is first reduced by contributions to your SE retirement plans and 1/2 your SE tax. if this leaves nothing left there is no deduction for SE health insurance. note we can not see your returns so can't say for sure this is your situation. another reason could be you have a net loss on schedule C or other sources that generate SE health insurance, if you are an S-Corp shareholder the SE health insurance must properly be included on your W-2. as wages.