From the shape of the leaves you can understand that propably is an indica dominant strain, hybrid most likely so some sativas genetics are there. I would say that is a light distance issue, that led to long internodal distance. That does not affect plants health of course, it looks great although the yield will be smaller. Is 3rd week in flower, is indica dominant strain and is auto so i think is late to take any actions. Give this beauty more light and let her do her best. Good luck!