I had come to the same conclusion, that I could never feel again like I did when I was a kid, that adult life was just inherently drab and lacking in feeling. But meditation did help, so I wouldn't rule that out if you could work it into your routine for a while.

What kind of meditation did you try? I found the simple kind most helpful: just to sit and pay attention to breathing and whatever comes along, and don't pursue thoughts once I notice them. It helped me with what you describe. I had basically decided that life turned grey when you became an adult, and all the thrill of experience was left behind in my youth. Through meditation I discovered I could still experience like I did when I was a kid, if I could experience without immediately going off into thinking about it. But I did meditate for a while before this started emerging. I never found the guided meditations or envisioning meditations to be particularly helpful, just sitting attending to ordinary experience.

I can't speak to whether you're clinically depressed and need some other help, but it might be worth continuing with the meditation alongside whatever else you try. I had given up on antidepressants too but eventually found a kind that worked. Now I continue the meditation but also take antidepressants when things take a real downturn. I hope you find something that helps.