I dont think u get an appointment in RPO, its just walkin i guess. They work on mon, tues, thursday & friday. they are off on wed, sat & sunday .
You can go to your district govt hospital & get the Govt district medical superintendent to put a seal & a signature (Attest) your SRS certificate & that will make it more authentic for the govt purposes. But i dont think they will give u a new SRS certificate, since they dint do ur SRS.
Choose what u want to choose in the gender column , dont let them dictate u, ur gender. U are free to choose either female or TG