Improving throughput of a Bluetooth Low Energy Connection
Are you sure all those packets are actually leaving the iPhone?
Maybe Apple imposes bandwidth restrictions on apps, as I told you on stackoverflow you should really ask this question in the Apple Bluetooth mailing list, where there are several helpful Apple engineers that could potentially help you.

Otherwise you really need to specify what chipsets you are using if you want to get something out of these questions.

EDIT: ok, you are using the CSR chipset, then I suggest contacting CSR directly and posting your question here:

https://lists.apple.com/mailman/listinfo/bluetooth-dev

EDIT2: a sniffer could certainly help you see whether those packets are actually being sent by the iphone and not being received by the CSR chipset, or else it is just that the iPhone is never actually sending them over the air