I am not quite in my early 60’s yet. I was baptized in 1988. I served as a ministerial servant and an elder. I gave my all for many years, but not nearly as many as you, and I started to question many things. The generation teaching, amongst many others. If I had not faded and left around 2007,I would have stormed out of the Hall when they introduced "overlapping generations." You are only "basically a non-entity" in the Kingdom Hall. To them, you are only as valuable as compared to how much you did for them this month, this midweek meeting, today. But you are valuable outside of that place to some people, at the very least to yourself.-
If I were to go back to the beginning of my postings on this forum, I can see that I was a bit disturbed that they weren't putting much effort into bringing me back to the fold. But I eventually realized I should be glad for that. It's a cult. Once they have no control over you, you are useless to them. But I managed to turn it around- They only have the control over you that you give them, so give them none.
Whatever your reason for being a JW, don't beat yourself up for "wasting" some of your life. You didn't know. And some other circumstances can just as easily rob any of us of our younger years- health, debt, addiction, family woes, being stranded on an island with Gilligan and a professor who couldn't patch a boat (or your life's equivalent to that).