I don't know what species it is, but I would say it needs more sun. Some milkweeds will bloom in the shade, but evidently not this species. Some say milkweeds are hard to transplant, but I have not found that to be true, or maybe some species transplant easier than others. The Asclepias tuberosa I have has been moved twice now, over the last 20 years, and it is doing great. Since these plants are fairly small you shouldn't have much trouble.