What's done is done, but, as a starting point I would not ever book a complex itinerary through a third-party website unless there were very significant savings over what the carrier offered itself. I also would use a travel agent unless I were experienced.

At this point, you have three carriers on three segments of an international journey and you do not have all of the information.

Your safest bet may be to go to a highly reputable travel agent and ask them to sort this out for you. They will most certainly charge you a fee for this service, but the downside risks for you are quite serious.