craftgrrl | 3d beading, thread help

I'm working on this 3D beaded chicken (right angle weave), it's a new pattern from a new book that I've never tried before, in Japanese...and the result is too floppy. The previous pattern I worked on had a bead inside to support it, but I'm not sure I can do it with this one, and it's also not in the pattern so I'm lead to believe it should work without it. Would using a stiffer thread work to make the form hold up better? And if so, do you have any suggestions? Currently I'm using 4mm Swarovski Bicones. The book says to use number 2 nylon thread, but I can't find anything #2 regarding nylon thread! If a stiffer thread won't help, I'll see if I can put suitable beads inside. The head shouldn't be a problem, but the body is oblong.

Thanks for your input!