You're just getting a stimulant high. In no way shape or form is this treating depression - it's just perking you up, as stimulants tend to do, and it is not sustainable. You'll likely start to get a crash as it wears off which will make things worse, tolerance will build and you'll need to up your dose, and in the end it is likely to just stop working. In the meantime you'll have depleted your dopamine and noradrenaline, which will exacerbarte any underlying depression.
As ephedrine has pronounced peripheral action, adverse side effects are common, especially with increasingly high doses - vasoconstriction and fast heart rate (not a good combination for the heart, even a healthy one), high blood pressure, reduced appetite (I know this is a desired effect for you, but it can go too far) and even kidney failure due to vasoconstriction of the renal arteries.
It is likely to start making you anxious, jittery and paranoid - not good for someone who is depressed - and as it is a stimulant it could potentially lead to stimulant psychosis, especially if you take high doses over any length of time. It can also cause insomnia, which will not help depression either. All of these side effects are dose-dependent, so they will worsen as you become tolerant and need to increase your dose to get the mood lift you need.
Overall it is going to make depression worse in the long run, while potentially damaging your health. I'd stick to using it at sensible doses for it's intended purpose only, and bear in mind the detrimental effect it can have on both your physical and mental health!
