@billandri Sorry to hear about your diagnosis and numbness issues. I would highly recommend asking for physical therapy with a therapist that practices McKenzie techniques which are geared specifically for getting things moving in the spine properly. I am not surprised using a neck collar didn't help, most often restricting spinal movement will make things worse, as joints are meant to move. I would also recommend looking at spinal injections. Sometimes steroid injections at the site of the issue (in this case C5/6) can be helpful in reducing swelling associated with the constant irritation and may give you symptom relief. (Again, not a medical professional, this is just my personal experience)
I can understand your hesitation on surgery, as surgery can sometimes lead to other issues. Most insurance companies want to see 6 weeks of more conservative treatment first before going for surgery. It might be beneficial to see a PT to help figure out if the stenosis symptoms can be alleviated with strength and posture exercises while also trying the steroids for reduction in inflammation before the surgery. If symptoms subside, you may opt for continuing down the non-surgical route. If they do not subside, the you will have done due diligence in looking at other options as well as satisfied any resistance you might get from your insurance.
I have had two artificial disc replacements at C6/7 and C5/6. I had the two surgeries 2 years apart and they were after quite sometime from the original injury. The disc replacement seemed the best option to me as it does not inhibit natural range of motion in the neck especially at a younger age. I would recommend doing research on surgeons using these devices first and picking one that has experience with a variety of devices and has been properly trained. Most of the time you can look on the device websites for a list of trained doctors and find one in your area. Both neurosurgeons and orthopedic surgeons specializing in spine issues may be options for this procedure.