From a personal point of view, it's great that your doctor is on board with you seeking treatment for your gender dysphoria. As long as you are stable on your medication hopefully you shouldn't face too many problems with that.
More generally regarding a link between gender dysphoria and bipolar disorder, a quick look at the literature turned up the following:http://gendersanctuary.com/pdf/TScomorbidity.pdf
Findings - Trans people have a similar rate of psychiatric problems (unrelated to gender dysphoria) to the general population. Of 435 trans people, 3 had a diagnosis of bipolar disorder. In my opinion, this looked liked a pretty well designed study using data about a decent number of trans people. Here's a summary of a study done in Japan with similar results - http://www.bioportfolio.com/resources/p ... order.htmlhttp://ajp.psychiatryonline.org/cgi/con ... 164/7/1122
This is really just a letter talking about a case study. For the person in question, manic episodes seemed to exacerbate the gender dysphoria and the authors would like to link both to some chromosomal abnormality. In my opinion, you can't tell much from one person. They refer to another study, also relating to one person. Can't get in to read the whole thing but here is the abstract: http://content.karger.com/ProdukteDB/pr ... tNr=224276
Again not very convincing and the abstract makes it sound like they would like to put all transsexualism down to 'psychosis-induced transsexual desires'.
So, there isn't much out there to suggest a link between bipolar disorder and gender dysphoria. However, we still know relatively little about the causes of both conditions. There are also a lot of issues with the diagnosis of bipolar disorder - some people think it is under-diagnosed, some people think it is over-diagnosed. My own guess is that they are not connected but there are a few people out there who, like yourself, are affected by both. If one or the other is untreated, then they will obviously have some sort of interaction with each other - you only have one brain after all!