If you think you are missing ammo there are likely two possible scenarios:
1) You haven't put in your payment card and waited at least 10 minutes for your old data to sync with the new system. Do this first.
2) Ammo that was in the old site on Backorder was mixed in with regular inventory now it has been moved to the Queue Tab in your crate and is separate from your regular Inventory. Check there next. View Crate -> Queue.
If you have checked both of those and still think you have ammo missing from the old website contact customer service.