Nice!
One quick note about hiding your love for junk food
People with BPD have no boundaries. So, part of loving you means that she expects you to become like her. Sort of a merger fantasy -- which may feel wonderful when you're on the same page, but hellish when you aren't. And being on the same page about everything is not sustainable, so the crash is inevitable.
You want to get back together with her and that's understandable. The key going forward is to help her tolerate the distress she feels when you are not behaving exactly like she wants (or demands).
There are skills you can learn to help with this. Some of this we do with words (validation) and some with actions (assert boundaries).
It takes a lot of strength to be in a BPD relationship -- she is going to lose respect for you if she is able to crush you with her emotional dysregulations. Losing respect will lead to devaluation.
The key is to know your values, your boundaries, and be able to weather her storms without making things worse.
It's a balancing act
Her breaking up with you is probably about something much more powerful than whether or not you scarf down ho-hos in your car
LnL