Given how easy the Philippines is to get to for you, is why I suggested it. My diving there has been in Puerto Galera and Dumaguete. Months of April, October and November. September is still good, although to your point, Tubbataha is not in your window. It is a small one in the spring and early summer (US spring/Summer).
I will be going back to Puerto Galera again this October/November. I love the diving there. There are a few other places I am considering, but I just find Puerto Galera to be good, consistent diving, super inexpensive, easy to get to and my topside experiences have also been outstanding.
I am going to take another couple of weeks to check out other places this November. Namely Palawan (Coron, El Nido) and probably Panglao. Puerto Galera will be all about the diving. The other locals will be a bit more topside stuff, touring, snorkeling, etc. and seeing how the diving differs, compares.