hey fabhz, I see why you're trying to put more light on this lady : to get the plant bigger and fatter right ? Problem is that you're in a 1L pot , the plant is 5CM at week 5 already 3 weeks into flowering my friend ! Much of the yield depends on the size of the roots and your plants roots have simply reached the edges of the pots already. It's basically too late to repot it or really even add much light to it. Next grow may i suggest a nice 15/20L pot, and a little nutrients. You'll see a huge difference even outdoors. If you want to add more light anyway, one thing you can do cheaply is use garden floodlights stack them up so it's shinning one the plant around 20CM away. Good luck man 🚀