Hi Genshai,
Dont know if this helps, but I had a similar problem where my teacher was always telling me I added too much 'filler'.
A way she explained to structure my responses really helped.
And that was to make sure all my sentences were based around showing cause and effect, rather than just describing explaining events.
So, my writing had to be something like: '__ happened, which caused __ because of __.' as often as possible, which prevented me from going into detail explanations about the events themselves instead, which keep on diverting me. And then you'd back up that argument with a quote/date etc.
It may not work for you, but I just found that forcing as much of writing as possible to be about analysing connections rather than explaining helped me get better marks.
ATB