Two thoughts come to mind. Your plant may be rootbound and can't take up water to the center of the rootball. Lack of sun won't make it wilt. If you are watering from the bottom up, that can make it worse. Try watering from the top down until you see water in the saucer. Then let the plant sit in the water for 15 minutes before you remove any extra water. The next day it shouldn't be wilted anymore. Now GENTLY take it out of the pot to see if it's rootbound. Take a look here.
It that's what you see then it's time to losen the roots and give it a new pot that's 2" larger.
I grow 2 different varities and one never gets direct sun and it blooms on and off. I use organic fertilizers. Sometimes I will put a tablespoon of milk in the water or use the just emptied milk container filled with water to give my plants a drink. I water when the top inch or two of soil is dry and they thrive.