welcome!
i think the problem is that you are only effectively one wall from the outside - so by distracting your mortars with giants someone could punch a hole into the middle with wb - layouts like yours are known as eggs - tough on the inside but once you crack them they are soft.
There are two alternative styles you might wish to try - there are examples in this thread .... if you have the patience to look:
A spider - it's an inner compound with spikes emanating from the middle which deals with wb .... i use a vaient of this, you can see it in my video - link in my signature.
A Beetle - it looks basically like a beetle... your important resources and th will be in the body and the legs protect from wb and slow attackers
Good luck and again welcome to the forums








