Hello Gita!
to ATP! Glad you found us, you seem to know what you're doing! I'm sure the cold could stop the violets from blooming but I would guess nutrients (as you were probably also thinking) and I personally think they like to be a bit root bound to bloom better? I know my streptocarpus and Sinningia both like to be pot bound and so when I propogate I know if I use a larger pot it will be a year or so until blooms! I hope the light works!
Cheers