Thanks for posting your query at DoctorSpring.com
I have gone through your question in detail and I can understand what you are going through.
I totally agree with you that bipolar depression is a difficult illness to live with and at the same time its a difficult illness to treat. The medicines that you are on are good and should have controlled your bipolar depression but unfortunately there is a relapse. There are some other medicines which could have been tried like Divalproex sodium, quetiapine, oxcarbamazepine. These options can be tried until no suicidal thoughts are there. If you get suicidal thoughts then there is no other option but going for ECT. You need not bother about the memory disturbances with the ECT. They are temporary and will not last for more than 6 weeks. At-least your suicidal attempts can be prevented by this. VNS has been successful in treating unipolar depression but not so much in severe bipolar depression. Further its not indicated when there re suicidal thoughts. Do discuss the above mentioned three options with your psychiatrist and get them prescribed. Otherwise ECT would still be the best bet for you.
Hope this helps,
In case if you have any further query, do let me know.
Dr. Srikanth Reddy