Well, I'm going to buck the trend by saying I only had a single queasy moment in my second pregnancy - compared to the first where I LOST two stone whilst pregnant because I felt so nauseous the whole way through.
Then I had a fairly 'normal' feeling sick from 7-14 weeks.
This time, the nausea mostly wore off by 12-13 weeks but has been replaced by food aversion/lack of appetite.
I think, what I'm saying in a long winded way is I don't think there is necessarily any rhyme or reason as to whether you'll be worse, or better, the second time. You could torture yourself with thoughts of it lasting for weeks and weeks more because other people have found that the case with their second pregnancies, but similarly, you could be just around the corner from feeling a whole lot better.
You've found the support thread already which is great (really, as grim as it all gets, the 'I'm not alone' thing is crucial, and so many helpful tips) so all you can do is try and get as much rest as you can (isn't it, anecdotally at least, accepted nausea/sickness tends to be worse when tired? Perhaps that's why it seems worse the 2nd time - running around after a toddler too can only exaccerbate things!) and plod on.
My fingers are crossed you do start to feel better soon!