I am at the bottom end of healthy BMi so I'm pretty small and I gained 18kg and by the time DD was 6 months old, I had lost 21kg. breastfeeding is the best diet ever!

What was really bizarre was showering in the first few weeks. Every time you get in the shower and feel your butt etc, you can literally FEEL that it is smaller. Really bizarre but awesome... LOL

Like everyone says, the important thing is feeling healthy and bub's health. My mum is teeny tiny and she put on 20-30kg with all 5 of her pregnancies and still (at nearly 60 years old) is less than 50kg so your body can def. handle the fluctuations.