Without knowing exactly where it was purchased, and based on leaves, this could also be a Daphne odora. Close ups of the branch tips will verify this. A source I read mentioned serissa leaves smelling bad when bruised, and blooming march - october. Daphne blooms at once in the winter and is a fickle, short lived little gem of a shrub.
What is the leaf size of Serissa?
I don't own one anymore, as the last one I had died when I sneezed near it. The leaves on this tree look just about the same size as a Serissa's leaf. The bark also looks the same.