Searching for my adopted sister

I am in need of a search angel. Afraid I don't have a lot of information. I am searching for my sister, born in 29 Palms, CA (Marine Corps Base) January 13, 1978 and given up for adoption in April/May of 1978. Birth name is Lyndi Lorenzen, adopted family name may have been Morrison. I have been looking for a little over a year with no luck. Any help or advice would be greatly appreciated. Thank You