Right now shes doing some crazy hcg diet and taking in 500 calories a day. It seems to be the only thing she can drop on supposedly. Doesnt seem too healthy to me. And she is doing cardio in morning after workout.
The diet is highly likely the reason why she is not making any progress - she's exercising heavily and she's well into starvation mode; her body is going to fight her for everything and not lose anything! It is far from healthy and not something that can be sustained for even a reasonable period of time. There is another thread here that touches on the HCG Diet:
http://anabolicminds.com/forum/female-fitness/128316-my-girlfriend-needs.html - definitely NOT necessary and certainly NOT the way to get maintainable results (sure, she will lose weight fairly fast, but she is going to lose a lot of muscle mass compared to bodyfat, and once she returns to normal eating, it is all going to rebound)!
With all due respect, the comment you made that you both "know a ton about training and nutrition" is very inaccurate, since one who is knowledgeable on nutrition (and training) would NEVER follow such a ridiculous and extreme diet - they would know how to EAT (and train) to get the results they want.
Your girlfriend needs to START EATING. She needs to take a good, long, hard look at her NUTRITION and target it sensibly and appropriately for fat loss for HER. Just to give an example, I am 5'1.8" and 115 pounds and I stay relatively lean all year round eating ~4,000 calories a day - more than many of the guys here eat for BULKING; your girlfriend does NOT have to starve herself to lose fat (if her exercise levels is high, she will have a reasonable Maintenance level, like I do), but needs to correct her nutrition specific for her for her goals and needs!
As I mentioned above, see my reply in
http://anabolicminds.com/forum/female-fitness/174350-girlfriend-cant-lose.html for more advice and information on what she should be doing.
~Rosie~