How do you know if it's time to release a bird?

Let me preface this by saying that I had the best of intentions, I understand about fledglings, and I made a tough call. I suffer from anxiety, and I just want to do what is best for this bird and I hope that desire is mutual and can unite us. 

A week ago, my dogs attacked the hedgerows at the back of my garden, where unbeknownst to myself, at least one blackbird fledgling had taken cover. I got my dogs back in the house and went to see what they had chased after, I bent down and saw the fledgling. The weird thing was, it hopped onto my foot and appeared to hold itself oddly. When I moved to nudge it off my shoe, it hopped onto my wrist. This to me is odd behavior for a wild bird, it was more like a hand-tame budgie. My mother and I assumed it had been hand-raised by someone and perhaps released too early. I left it in the hedgerow and watched for birds to come and visit it. I watched for over four hours and saw no birds visit other than a few pigeons on my bird table. 

We decided we should put it in our empty Aviary to protect it from predators, and to keep an eye on it until it was better. I now know I should have got advice at that point, I kick myself for just following my mother's well-intentioned lead instead of actually using my own initiative but I was uneducated and I thought we were doing the right thing. Ultimately, it's a wild bird, it belongs in the outside world free of cages no matter how big and I am heartbroken we may have done so much damage in trying to protect the bird. 

It's a week later, and I'd hazard a guess that the bird is now about 25 days old, and it is doing better without any weird posture or sign of injury like when we found it. Despite its odd friendliness towards us, I do not believe it has imprinted on us since it was not a nestling when we found it and it already exhibited the behavior. Over the week we were very hands-off, and it has become much more independent, it no longer sits and waits for food and no longer demands our presence, and even though it jumps onto our wrist/arms/hand sometimes when putting/fixing something in the aviary it is much less interested in us and will hide or flee if it's on the ground, or simply sit on its perch and watch us most of the time. 

I have concerns, and I know it's probably my anxieties but I don't want to make another mistake. I want to release the bird, but I'm worried it won't find food for itself or know how to protect itself. I cried over my dinner tonight worried I may have done the wrong thing. Trust me, I don't want to be in this position again, and I don't need telling how stupid I've potentially been.

So is it safe to release this bird? Will it be able to learn to find food,defend itself and find other blackbirds? Or is it not a good idea to release, and if it's not a good idea, what next steps do I take? I just want to do the right thing.

Thank you in advance for helping guide us, helping us do right by this bird, and for your understanding.