In there you need to edit your:
In the General section:
Home Address : Use USA as Country and PR as State.
Billing and Shipping Adresses:
Delete all your addresses and ad a new one with the same format (PR as State, USA as Country)
In your left there's a Payment Methods section:
Delete the credit card info you have an create a New one with your Credit card and the billing address with the format (PR as State, USA as Country).
BOOM! Done!
Now, like I said. You need to do this from a 3g connection, for some reason when I used Wifi I couldn't select my address on the check out. USE 3G!