I know a 40-year-old Cricket (yes, nickname for C.) and she does just fine. I also know a 38-year-old who decided that her name did not fit her and changed it. She sent out a very nice email to all her friends and acquaintances saying, essentially, "I've been doing a lot of soul-searching and I truly feel that my given name does not fit me or my life, so I have chosen a new name for myself, please call me _____ from now on."
Yes, it'll be a little weird. Yes, some people will judge you for it, but do you really want to hang out with those people? Try to have a sense of humor about it, when telling people, and reintroducing yourself to people, and when people call you by your old name, gently and with humor correct them.
Speaking as a someone equally plagued by a common name (in my 4th grade class of 26 kids, SEVEN of them were Jennifers), I feel for you. When I was first in my 20s, I felt like I should start calling myself "Jennifer" as it would be more "grown up" but in my early 30s, I realized that the name that feels like *mine*, that feels like who I am, is "J." and so I got it printed on my business cards and haven't looked back. People continue to re-nickname me all the time (the people who will call me Jen no matter what I say, and then there are those who persist in called me JEANie) but I just gently correct them and move on.
So start calling yourself Cricket. Ask your friends to call you Cricket. Introduce yourself to new people as Cricket. When you go to the doctor, and they call your given name, just say, "Please call me Cricket." Go for it!