How do you know if your rabbit is definitely pregnant despite not being big?

To determine if your rabbit is definitely pregnant without noticeable size increase, you can check for behavioral changes such as nesting or increased aggression. Additionally, palpating her abdomen gently after around 10-14 days post-breeding may reveal small, marble-sized lumps where the developing kits are located. A veterinary ultrasound can also confirm pregnancy early on. If you're unsure, consulting a veterinarian is the best course of action.