I think it's much, much simpler than that.
Are, by your own judgment, the rewards of your life adequate compensation for the travails?
If the answer, using your own benchmarks, is no, then the honest reality is that your life is a net-negative experience.
This net-negative status probably accounts for literally billions of human lives taking place right now.
Step two is to determine whether this net-negative experience is best addressed by terminating it of your own volition
or by dealing with it in another way. In the making of this decision, once again, no other values are relevant but your own.
One thing is for certain. A society that does not sanction humane euthanasia or assisted-suicide is lightyears away from becoming civilized--and that includes ours.
the value of human life is not absolute.
It's to be appraised in qualitative terms like the value of anything else.