On your return, just don't enter the 1098-T and/or 1099-Q. It's too complicated and TT has flaws. You have more than enough expenses to cover the 1099-Q.
You're trying to breakdown the numbers more than they need to be. Your expenses are $11,246 + 8318 = 19,564* and that's more than the $15,713 529 Plan distribution. Since you're not claiming the tuition credit, that's all there is to it for your return.
On your son's return, he has 19,564 - 15713 (used for your 1099-Q) = $3851 of qualified expenses for his scholarship. $7395 -3851= $3544 scholarship is taxable. If that's his only income** and it's less than the $12,550 filing threshold, he does not need to file (or enter the 1098-T).
For more detail on 529 Plan distributions, see https://ttlc.intuit.com/community/college-education/discussion/re-why-is-my-college-student-paying-t...
*You don't mention books and required computer, which can increase those expenses.
** If he has other income from wages, the $12,550 threshold still applies. If he has unearned income over $350, it gets a little more complicated.
