Oh my goodness. My heart goes out to you Nagichan.
Please take comfort in knowing that you have done all that you could for them. Terragon and Anise most likely suffered from birth defects. Paprika's passing is an unfortunate accident that, if you could have foreseen it, would have prevented. Or she too could have died from other issues. You will never know.
I hope the three boys will be adopted. Too bad you have to rehome Nutmeg (any chance that you might keep her and adopt some female companions for her? or, if Cinnamon has been neutered, could he be put in with her and the other two boys, Masala and Chai, share their own cage?). I am on a forum called deguworld. Are you on it? There is an Adoption Page where you can list Nutmeg; as well there are quite a few Canadians there to that might be able to help.
Good to hear from you again though too bad it is with such sad news. Though there is happy news too – Nutmeg, Cinnamon, Masala and Chai are doing well. Please keep in touch. Wishing you all the best.