Steve....amorphophallus are not like typical plants. They do not 'grow' during their active phase (when they have leaves). They come up out of dormancy with the stem/group of leaflets fully formed (botanically it is considered one 'leaf'). This will be all it does that entire season. It does not get any bigger once fully opened, nor does it grow more leaflets. During this time, growth goes on under the ground in the corm which gets larger. Then dormancy for several months. Then, it will send up another 'leaf' for a new season. It continues this each season till it is large enough of a corm to bloom. That season, it will bloom and seeds will ripen (typically no leaves during that, but some varieties do).
So yeah...don't expect either of those to get 'bigger' this year other than the left one opening up more. Each active phase will produce a larger leaf, but you still just get one per season (although I've had some send up 3 or 4 stalk/leaf).
I grow A. bulbifer, A. konjac and had pseudodracontium hermandii (now Amorphophallus, from what I understand), but it rotted last fall after it was dug up and I think it's dead now.
Here's my konjac last summer:
Opening.
Two weeks later.
Corm is now the size of half a basketball. It's sending up a bloom currently, hasn't opened yet, but the stalk is already over a foot out of the corm. Also have bulbifer seeds still ripening from a bloom last spring (right). Looks like I'll get another bulbifer bloom this year as well.
Bulbifer flower last season:
