BS was my last exam and thankfully, I passed! I do believe you should not take BS as your last exam however, because I did get a number of BS related questions on other exams, especially BDCS.
I did use AMBER seminar and it was a great starting point but should not be used as your only form of study material. I used it in combination with Jenny's notes and some of MEEB, mostly for diagrams. I did start reading Ballast for this exam but did not find it as useful as I did for the others.
Note that the AMBER book diagrams are not similar to those in MEEB and NCARB uses these MEEB diagrams on the exam. It is important you become generally familiar with these diagrams.
Best of luck and success!