Im a size 18/20/22 and the bar on hex was really heavy on my tummy! Felt like I couldnt move at all
Oblivion I asked for the bigger seat before I went on, but I had loads of room and could have gone in a "normal" sized seat! Though I felt I had to really push my thighs in!
Rita loads of room, didnt attempt Air, nor did I go on Nemesis.
The Mine train was fine, but I still felt abit squeezed in, if im honest, but I have quite long legs as im 5"11 so I think my long legs had something to do with that too! I would have rather sat by myself there, but had my little boy with me!
Oh and Duel the bar came down onto my tummy aswell, but wasnt uncomfortable.
I was dead stressed about going on the rides because of my size, which is why I only went on Oblivion and Rita, I didnt even go on thirteen because it looks so tiny in the seats. I had such a good day though, and it was more probably in my head than anything else.
I hope this helps :D