Monica was not ever 'chubby' before the stabbing. Her peak was at the Oz open in '93.
She was not in brilliant shape in '96.
I agree her worst time was in '97 but this was understandable - she never even practised whilst her father was deteriorating. Very sad, especially since, as some people have said, the press made fun of her for it.
One thing worth remembering though is that aside from her weight (although the two are linked obviously) there has also been lots of longer term different injuries that have afflicted Monica. Off the top of my head:
shoulder injury, twisted ankle, chronic foot problems (the most serious imo), etc.
The weight issues have most likely attributed to some of the injuries but the fact that some issues have prevented her from training fully will affect the weight - chicken and egg scenario.