Although I am not light like you I also enjoy being fit and doing triathlons - I did my first Olympic distance when DD was 9 months old.

With DD I ended up putting on 18kg (however I had already lost 10kg by the time I left hospital). This time I wanted to put on less but I think I have already put on more - 6kg at the 18 weeks mark. I had very different symptoms this time with m/s and had to eat constantly for the first 13 weeks so as not to vomit or pass out.

I am trying to slow it down now but not sure if that will work. The only thing that I am clinging to is that running around after a toddler and a baby will keep me pretty active and hopefully i will drop the weight after the birth.