In my opinion, the sentence is fair.
It's generally agreed that there are three purposes to imprisonment: deterrent, reform and retribution.
Reform: She's going to be away from her child for a while; she's going to have a miserable time in prison; life is going to be harder with a criminal record - employment, travel, finance etc. I think she'll find plenty of reasons to not do it again.
Deterrent - Yup, the above pretty well acts as a deterrent to me. I would avoid doing something I felt might lead to ending up in prison.
Retribution - Is this something we want in a civilized society? I would rather someone was reformed and making themselves a valuable of society, rather than rotting in prison at huge cost. If you want retribution in this case, should we go biblical? An eye for an eye?