That level of activity with 1000-1200 cals is starvation, your body isn’t going to let go of anything, and you’re making it worse. You need to get your RMR up, not eat less.
No disrespect, but the “healthy fats” is the clue she doesn’t know what she’s talking about, unless you’re regularly trying to add trans-fats to things. A lot of people are very much stuck in a time of debunked nonsense from a decade ago, but that’s your fight to fight. The links to Cholesterol and CVD are debunked, Cholesterol removed by the UDSA as a “nutrient of concern” almost 10yrs ago now.
Are you doing any resistance training or only cardio stuff? Kinda of recipe for disaster if you are.