I personally would go with Keely instead, maybe even as a nn for Keelin, so you keep the vibe, but freshen it up :)Wdyt? But don't go with Kelsey/Kelsie/etc. It's like the 2nd Kelly & waaaaay too trendy.
Keely and Keelin are waaaaay (you had 5 a's in there right?) too trendy as well. It isn't just Kelsey that is trendy. Compared to those names, Kelly is downright awesome.