I will first echo a lot of what you've already heard, which is if you're not intentionally losing weight, aren't happy about your diet and can identify anxiety/depression as causes of your loss of appetite (a common symptom in both!) you should try to find a professional that can help if you can't increase the calories on your own. A doctor, counselor, psychiatrist, psychologist or even nutritionist could be a great place to start. Being at a healthy weight is great but losing weight to fast can be dangerous independent of any other mental concerns that may be going on.

That said, if you can't, won't or just aren't ready to seek help for issues do what you can to 'force' yourself to eat at minimum the calories you need to maintain your weight as it is now. Track what you're actually eating and make sure you at least hit the goal number of calories. Keeping around healthy but calorically dense foods like nuts or peanut butter can make it easy to get in a couple hundred calories quickly without really feeling like you're eating much or "getting full"

It's hard to make specific comments without seeing your diary but make sure you're realistic with yourself about your goals, expectations and what you need mentally and physically to get and stay healthy!