How well will my byu credits transfer to a UC school?

Ive been at BYU for two semesters now and I want to transfer to UCSD next year. I've heard that credits really dont transfer well from BYU to the UC schools. Am I basically going to have to start over? I know there is a TAG program but I don't really want to go to a community college for two semesters before I can get into UCSD...