Thin Naga Jolokia plants

Hello! It’s my first time taking care of chili plants and I don’t really know what I’m doing wrong with these. The stems are looking thin and the leaves are pointing downward. I give them nutrients every now and then and try to keep them close to the light source (see ruler). The soil is mixed with a little sand (~10%) to keep the soil porous.

What am I doing wrong? I know they will have to be re-potted, so I will do that. Any advice on how to best do it? Can I cut the leaves furthest down and put them deeper in the soil to make the plant more robust?