Hi,
You did the right thing of taking them back to their original owners and keeping you off from stressing the puppies and yourself of course. Coping with depression and anxiety with pets that does not suit you could add up to your condition as well as risking the puppies' normal growth surrounding. Although generally puppies are asorable little ones, their hyperactive ways could stress you out and as you say you might not be able to manage.
But still, do not loose hope in raising them. Your timing is probably not right as this might be not the right time to have them because of your condition. Puppies like kittens are adorable animals. Try some other time first with a single one and once you get used with their ways and bonding with your kittens then add up one by one. I'm sure before you noticed them you are raising them all together amazingly. Raising these pets are the most wonderful thing in the world. It helped me find joy and happiness as it cures away my depression and relaxed my spirit. I became more joyful and cheerful and help me to worry less from all the problems I've had. 
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