I feel exactly like you do. The way you describe this is perfect. I'm always tossing around in my sleep and I feel half asleep half awake. The best part of the description is that you wake up constantly and feel like you've been sleeping with your eyes open. That's exactly how I feel.. I've been to 2 sleep studies and diagnosed with mild sleep apnea.. You should definitely check that out..
There are lots of things that can interfere with sleep. Stress. Medication side effect. Thyroid. Some mood disorders. Sleep disorders - often obstructive sleep apnea or limb movement disorders. Some blood tests then a sleep study might lead to answers. The feeling if being stuck somewhere between asleep and awake is not the same as insomnia. It sounds like your sleep stages are being disrupted, not allowing you to reach the deeper restful stages of sleep. My personal (not professional) opinion is that if the medical tests are normal, I would have an overnight sleep study in a lab to try to find out why this is happening, and would not be comfortable taking meds to sleep without knowing what's going on.