I think it is too much. Have you read the children's book Chrysanthemum? It's about a little girl who gets made fun of for being named Chrysanthemum until her teacher says she loves it so much and names her baby it. Then all the little girls in her class want long, fancy flower names.
I think the logical nickname would be Chrys /
Chris / Chryssy /
ChrissySandyAnnSan