Canna terra has quite a high ec/nutrient content i think although a while since i used it.
Did you just cut the top of the bag and transplant and water the whole bag, because thats what it looks like.
Probably small due to overwatering and keeping the light a bit close but after two weeks growth and only attaining that size there could be a whole host of problems.
Maybe try simplify things for the next grow and ease up on anything that could be stressing her.
The plant problem threads are a good place to gain some help as well as the countless cfl grow journals