Decrease in weight and stagnation

I lost 4 kilos. At the moment I weigh 58 kilos at a height of 1,61m. For 3 month now nothing is changing. I would like to lose another 3 kilos. I do more exercises, kept my nutrition and furthermore I drink a „slimness“ herbal tea. What can I do ?

Bravo, congratulations. To lose weight without gaining it again is already very good. You must definitely continue!
Your body got used to your new eating habits, which apparently is a perfect amount of food, as your weight is stable. Carry on holding on to those amounts, they mark the normal amount, which will stabilize you later on.
If you want to lose another 3 kilos, you must carefully try to reduce your current daily amount of nutrition about 300 calories within approximately one month, especially at the expense of the dinner, which can be limited to a small salad with a side dish, fruit and herbal tea. You must continue physical exercise, eat a substantial breakfast and lunch. When you have reached your desired weight, slowly begin to ingest your current amount of food, for that your weight stabilizes at around 54 and 56 kilos. In that way you will not have anymore big fluctuations in weight, which are harmful for the health.