Light and water

If that's the case with the lighting then it is 100% the reason why the plant is slow-growing. It's just not enough light for vigorous growth. Adding nutrients won't cause growth to increase at this point. 250ml of water is such a small amount for that pot size. Especially when using a pot that has tons of airflow like an airpot. Fully saturate the pot until a little water drips out the bottom of the pot. Then once all the medium is wet, lift the pot and feel its weight. Now every time you move the pot outside and inside pay attention to the weight. Once the pot is very light, it is time to water again. Letting the pot reach a proper level of dry between waterings is what will help prevent overwatering. now if the pot is decently dry and the plant is drooping then it is likely thirsty and its time to water. You likely won't be watering on a set schedule as the plant will dry out at different rates depending on how much the plant drinks, how windy it is outside, the temps and humidity. So you may water 3 days since last watering 1 time, 4 days the next, and then 2 days the next. As long as the soil is reaching a good level of dry between waterings it doesn't matter if the time between waterings is consistent. Once again, feel free to dm me if you wanna talk about things or need some advice.