If your application is scheduled (to be scheduled) for an interview, it means that's not considered as a routine process. The average processing time do not apply to you.
Your post is long but it doesn't give any details on your application. (Where PA gets biometric and medical done is NOT relevant)
E.g. how long have you been in a relationship with PA. Are you applying under common law or spousal (married).
Is that an arranged marriage? How long have you known each other? How many time you visited your spouse/partner.
Was a traditional celebration done or was it a court marriage if married.
etc.
