Unfortunately, you will have to apply for confirmation of Permanent Residence before you apply for naturalisation as a UK citizen. This is because of a rule change in November 2015 which requires that all EEA applicants must first apply for confirmation of their PR status before they apply for naturalisation.
So, you will have to apply for PR. Details on how you can do this are on the following page:
If you are not married to a UK national then the requirements that you must meet are contained on the following page:
If the home office confirm when you obtained PR that you are regarded as having obtained PR some time ago then you can apply for naturalisation without waiting a further 12 months from the date your receive your confirmation of PR.
However, if the home office are silent about what date you should have been regarded as holding PR and simply send you a permanent residence card then the best thing to do would be to wait a further 12 months before applying for PR to be on the safe side.
I am sorry, I’m sure you find it frustrating.
My goal is to provide you with a good service. If you feel you have received anything less, please reply back as I am happy to address follow-up issues specifically relating to your question.