My friend was showing on her first at 8 weeks! She looked full term by 16 weeks but the growth seemed to slow down rapidly and she went a week over without being too uncomfortbale if that's any consolation. Her little girl was born at 7and a half lb and perfectly healthy and gorgeous. Maybe your little ones will slow down and even out the second half of the pregnancies!
I haven't been able to stop eating this week, from when I wake to when I sleep I am constantly grazing so I don't think it will be long before I balloon out too. My mum said that with me she was showing from the start and people thought she was having either twins or a baby elephant (charming), but with her second, my brother, she didn't show til 6 months and then he just arrived overnight! Pregnancies are so funny. I think judging by mum's experience I;ll be having a little boy, as her sister's experienced the same re showing with boys and girls too.