When the IRS recalculates your tax return they will adjust the American Opportunity Credit. Do not file an amended return.
I don't know why you think your refund should come in July. The IRS says it will take all summer to send all the refunds. Summer ends September 22, and it could turn out to take longer than they expect. Since adjusting your tax return requires recalculating the American Opportunity Credit, it will be one of the last ones that they do.
