Are you allowed to call or e-mail her in between sessions? Maybe you could call or e-mail and either say that there is an issue that you feel like you want to get out before your next session. Or just say you would like to see her earlier than three weeks b/c there is something I want to share with you.

Don't worry about seeming annoying or too dependant.. she is a T and well she is used to people depending on her!! It is good that you feel you can trust her enough to share your SI issues with her.