Between your exocrines and tervigons you have a lot of anti-infantry already, its one of the things I like about your list.
I would swap 1 pair of TL devourers off of each of your fexes and replace it with a heavy venom cannon. That gives you 3 str 9 shots at any tank that doesn't fly and is still a template so can still be used as anti infantry. Also, easier to wound things like wraithlords/knights should you need to shoot at em.
I would equip your Prime with Talons, Whip, Bonesword, and flesh hooks for a few reasons. One, to take out characters with power fists so they can't take out your fexes. Two, with an initiative of 8, you're going to be catching and cutting down any enemy unit that knows fear. Three, he's not going to be contributing much to the shooting anyways!
You'll need another 15 points to pull this off so the only thing I can suggest is to drop the beetles from your tervigons. I would keep them back a bit anyways as they're your scoring synapse and you should be keeping them safe anyways.
Then you'll have another 5 points for something somewhere.... hmm. Maybe give a fex spine banks or give your Prime a deathspitter instead of talons as he has plenty of attacks base anyways.
What do ya think?