Whatsapp files to new phone
You can probably install WhatsApp in your old phone again and check if the chats are still available. 
If they are available, save a backup to Google drive as well as on your phone and then try again by reinstalling on your new phone.

Check when the latest backup was created automatically by whatsapp either on your old phone or Drive. If there's a recent copy you can copy it into your new phone and try retrieving the chats while reinstalling.

If none of the above works, I think you lost your chats.