I see that you already have the META statements for 'pragma' and 'cache-control' in your page.
Carterlake had posted on the old forum that what is really needed is to emit the expires and last-modified headers too (I do this on all my pages). Put this at the top of your page:
<?php
header("Cache-Control: no-cache,no-store, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");
$NOWdate = gmdate("D, d M Y H:i:s", time());
header("Expires: $NOWdate GMT");
header("Last-Modified: $NOWdate GMT");
?>
Best regards,
Ken