I'm not sure what gender you are (no offense), so I'll give suggestions for both male and female. If you're female, then it's probably some form of "
Christina," "
Kristen," or "
Kirsten." If you're male, then it's probably one of these, which I got when I looked up your name on the database:
COSTANTINO m Italian
COSTANZO m Italian
COSTIN m Romanian
CYSTENIAN m Welsh
KISTNA m Indian
KOSTANDIN m Albanian
KOSTYANTYN m Ukrainian
Or, I should think, the name "
Carsten."
Hope I could help.