Greetings, and thank you for your question. If the only symptoms you have are losing sleep, initial insomnia (trouble getting to sleep), and racing thoughts, it would be premature to say that is bipolar disorder. Certainly, elements of those are present in a bipolar disorder, but the disorder is also characterized by extreme moods, abnormally-elevated energy, uncharacteristic distractibility and verbosity, and a decreased need for sleep, among other things. The presence of racing thoughts and poor sleep can be present in non-bipolar conditions, such as anxiety, ADHD, agitated depression, and just normal life stressors, too! With that all being said, let's move on to the use of Seroquel. Seroquel's indications are for schizophrenia (not you from what we know), bipolar disorder, and to augment in depression. It is also used "off-label" to aid in sleep because it tends to be sedating. However, it has a lot of potential side effects, such as weight gain, cholesterol increase, and blood sugar problems.
I think it would be helpful for you to have your doctor evaluate you for the presence of bipolar, anxiety, etc.
If the inability to turn off your mind and the sleep disruption are due to a mood disorder or anxiety disorder, for example, treating the underlying problem will correct the sleep and racing thoughts. If, however, this is "just a phase" and due to life circumstances, I can think of better temporary options.
Hope this helps! Please let me know if I may be of further service.