🔨 Fix monthly recurring event for given occurrences

lib/src/modals.dart

@@ -101,13 +101,29 @@ class RecurrenceSettings {
   final List<int> weekdays;
   final List<DateTime>? excludeDates;
 
+  /// Calculates the end date for a monthly recurring event
+  /// based on the start date and occurrences.
   DateTime get _endDateMonthly {
-    final occurrences = interval ?? 1;
-    return DateTime(
-      startDate.year,
-      startDate.month + (occurrences - 1),
-      startDate.day,
-    );
+    int occurrences = (interval ?? 1) - 1;
+    DateTime nextDate = startDate;
+
+    while (occurrences > 0) {
+      nextDate = DateTime(
+        nextDate.year,
+        nextDate.month + 1,
+        nextDate.day,
+      );
+      if (nextDate.day != startDate.day) {
+        // Update date
+        nextDate = DateTime(
+          nextDate.year,
+          nextDate.month,
+          startDate.day,
+        );
+      }
+      occurrences--;
+    }
+    return nextDate;
   }
 
   /// Returns the calculated end date for the selected weekdays and occurrences,