Not all doctors are familiar with its use in this way. When I had to switch doctors after mine retired, I had to educate them in its use so that they would continue prescribing it.
It is also not an automatic approval by insurance companies. However, if denied by your insurance, you can get it at a fairly reasonable price using GoodRX.
If you're still struggling after what you're already one, and have gone through a few other options (and maybe even if you haven't) then I would highly recommend talking to your doctor about this.
Something to keep in mind though is that this will, mostly in the first week, impact your sleeping patterns. Taking it first thing in the morning would be the best time, and perhaps ask your doctor about using an over-the-counter sleep aid such as diphenhydramine during initial usage.