I have the same problem but not as bad. I usually sleep about 5-6 hours and wake up about twice. It all started to happen when I had a bad week of stomach pains and acid reflux. Even when I felt sick i was sleeping good but after i felt better my mind would not shut off as i would lay down.Also im constantly aware of my heartbeat when lying down and can feel a pulse on the pillow and behind my ear. I think the primary insomnia that i had turned out to be got worse cause i continued to obsess about if i was going to sleep or not. I probably have some type of anxiety problem but I just learned to live with it.
Try taking 1000mg of calcium after dinner. Calcium should be accompanied with 300mg or more of magnesium. You might want to find calcuim in a capsule rather than a tablet, or take any brand of coral calcium as long as it is in a capsule and accompanied with magnesium (vitamin D is an added bonus if you can find one). Capsules dissolve in the stomach more completely than tablets, which is good especially since you are taking them in the evening. In a day or two you should be sleeping much better.
A natural remedy you can try is melatonin 30 minutes before bed. It takes 2 weeks to get the full result. For myself, I take 50 mg Zoloft before bed. I was not depressed either, but my Dr says sleep problems can be caused by low serotonin levels. Another possiblilty is that your hormones are out of whack due to the Oophorectomy. Have you tried hormone replacement?
It's time for a prescription medicine. You may not be thrilled with the idea of taking it but often times they work the best. You might want to try Elavil or Trazadone, a small dosage at bedtime. I have chronic insominia and been taking trazodone for years, it helps me fall alseep. If that doesn't work there are so many new medications out there...Lunesta, Ambian, Sonnata..your doctor can probably give you some samples to try. I know about the depression from lack of sleep, you owe it to yourself to see your doctor and get some help. Don't worry, doctors dx and treat sleep problems all the time.