Infusion systems, infusion devices, and related operating methods are provided. An exemplary method of operating an infusion device capable of delivering fluid to a patient involves obtaining, by a control system associated with the infusion device, an input meal indication, obtaining historical data for the patient associated with the input meal indication, determining an estimated carbohydrate amount corresponding to the input meal indication based at least in part on the historical data, determining a bolus dosage of the insulin based at least in part on the estimated carbohydrate amount, and operating an actuation arrangement of the infusion device to deliver the bolus dosage of the insulin to the patient.