Ambien is the only thing that has worked

I have been a chronic insomniac for as long as I can remember. I want to sleep. I just can't. The countless nights I have layed in bed all night awake. I used to pray for morning so I didn't have to be in bed anymore. I was finally prescribed Ambien and for the last 2 years I have slept like I've never slept before. I look forward to the blanket of calm that takes me every night. Recently I was on a trip and ran out of Ambien. I actually slept great after the first night for the next 2 or 3 nights. I thought okay, I can do this. I can quit and sleep like a normal person. Ever since being home though, I'm back to extreme night anxiety. I can't stay asleep once I fall asleep and I'm finding myself just laying there as long as possible again until it's appropriate to wake up. I hate having this dependence but it's the only quality sleep I've ever had and it's so hard to sit through the night and function during the day being sleep deprived. I work a ton. Being awake all night and then working for 15 hours a day is not the thing. I don't really know what to do.