Technically you don't have an FAA instrument rating as you haven't passed the FAA IR practical -- you have a 61.75 private pilot certificate with instrument privileges (which is only valid at the PPL level), plus an FAA CPL.
To obtain a standard FAA IR you will need to meet all the requirements of 61.65, including both written and practical exams.
Assuming you have the necessary flight hours (including the 250nm instrument cross-country), 61.65 requires at least 3 hours of instrument training with a CFII within the preceding 2 months, an endorsement from the CFII that you are ready to take the practical test, and passing the actual instrument checkride.