Actually nicolaou my reading of your post is that this is the most significant factor in your alienation from JWs:
Of course I found I couldn't have a free and open discussion about these things with my Mum or 'brothers and sisters'. I began to feel isolated and was soon on my way out.
Not the details of doctrine itself, but the culture of not being able to discuss problems. I can relate to that.
I will point out that we live in a culture that values being able to question authority and express different viewpoints. This runs right up against JW deference to the GB. If you accept the dominant values of an open society including open discussion and questioning authority, this is bound to undermine the JW belief structure. The actual points of contention are (almost) immaterial.