I try not to look back at what may have been lost in the years I spent as a JW. I'm happy enough to have gotten out and gained my freedom and a fuller control of my life than I ever had. I can't change the past, I can only live in the present and plan for the future. So I'm happier by doing the latter two and minimizing the impact of those lost years.
Thankfully for me as a born-in, I went into full rebellion mode in my teen years and was completely out by age 15. My parents passed away decades ago, and besides resenting the WT for stealing the happiness from my childhood, I also hate the WT for depriving our family of quality family time. But the damages caused by the WT are what economists refer to as "sunk costs." There's nothing we can do to change what has already happened; we can only "move ahead" (Song no. 63 from the 1970s songbook) by learning from the past and living what's left of our lives to the fullest.