If the plan was not established by the business, the business did not pay the premiums or reimburse you for the premiums and report on a K-1, then you may have to report on a Schedule A under the itemized deductions as a medical expense, which is subject to the 7.5% rule you mentioned, this is according to the information I have found on the IRS website. The IRS also has an article on not missing Insurance deductions. I would check this article out to see if any of the situations apply to you, may be helpful.
https://www.irs.gov/newsroom/dont-miss-the-health-insurance-deduction-if-youre-self-employed
https://https://www.irs.gov/taxtopics/tc502/taxtopics/tc502
https://turbotax.intuit.com/tax-tips/tax-deductions-and-credits/tax-deduction-wisdom-should-you-item...
Hope this information helps.
