Before we call it a "gap", which specific "reports" are you talking about? There's a big difference between retention requirements for "management reports" vs. "regulatory reports/records".
Based on the weekly reviews you've described as missing, it sounds like your problem is related to "management reports" or "workpapers" (for lack of a better term). Unless you dictate as much in your policy, there is no specific requirement to retain those for any amount of time. For example, if you review a daily large cash report to identify the need for CTRs, those are not directly required to be retained - only the CTRs are. I stress the term "directly" because your "workpaper" retention practices will be evaluated by examiners under the internal control pillar and a failure to adequately document your analysis and decisions will easily get you in hot water. The best practice I've seen tossed around, relative to "workpaper" retention, is to retain from exam-to-exam at a minimum. Maintaining five years of workpapers is not imprudent.
In your circumstance, it would be prudent to report the issue to a management oversight committee (e.g. risk, audit, etc.) and have a documented review that captures the scope of missing documentation, a manual lookback, identification of any control weaknesses, and a resolution to all of the problems you've identified.