Welcome to the Fido Community @Urieka!
I totally get how the numbers can seem a little confusing, let me explain though
Based on your screenshot, the plan you have includes 8GB of data and you have a 2GB bonus making a total of 10GB of data.
The section that says "extra usage" does not include the bonus, this is why it shows 99MB. If you look at your total usage you're at 8.09 this is why
It's definitely a little confusing and I'll pass along the feedback. Rest assured you aren't over though as you have the 2GB bonus!