I dont buy those measurements either. The first pic you posted suggests there is more room than that as the van is parked parallel to other cars parked on the same side of the road as rhe red one in the picture.
I think you can do a a 3 or even a 5 point turn reversing back to the left and avoid her grass.
You are causing the arguments. If you had to move your shed, it mustnt have complied but apparently the neighbour was unreasonable. You are cutting up the grass, but again she is apparently the problem by complaining about it.
Yet you come on here and whinge about her. You appear butt hurt that the thread has not gone the way you thought it would and most think you are not doing enough to avoid the problem or the conflict it is causing.
Either speak to her and explain its unavoidable (apparently) or perhaps try some of the suggestions.
Personally i think you couldnt give a shit about your neighbours and so are making no effort.