The health insurance that you are provided is non-employee compensation and is income from self-employment. The sum of the deductible portion of self-employment taxes and the deduction for self-employed health insurance is not permitted to exceed net profit from self employment.
Health insurance is a business expense on Schedule C only for those payments made for non-owner employees, of which you have none. The reason that impermissibly entering as a business expense the amount paid for your health insurance makes a difference is that it inappropriately eliminates your self-employment tax.
Finally, it seems unlikely that the insurance provided by your former employer qualifies as being eligible to be claimed as a self-employed health insurance deduction. To be eligible, the insurance must be in your name or the name of your business. The amount can instead be claimed as a medical expense on Schedule A if you itemize. From the instruction for line 17 of Form 1040:
The insurance plan must be established under your business. Your personal services must have been a material income-producing factor in the business. If you are filing Schedule C or F, the policy can be either in your name or in the name of the business.
