Final bitter attack too easy

[AgentDove]

I was expecting half my base to be destroyed with me standing over a pile of dead biters, my solar farms being severed from the network bringing all the load onto my small power plants, robots scrambling to rebuild, makeshift turret blocks being erected as rapidly as possible. And me actually contributing to the fight.

I just left Factorio running in the back ground while i played world of tanks.
The worst thing that happened was that my trains got clogged because my blocks weren't bigger enough.

simple solution would be to have more and more bitters sent if the wall isn't broken through, and then ease off the amount of bitters. And if that fails, spawn a worm on the turrets.