I got my class 2 within a month (this is also delayed due to issues) and the doc gave me the documents and told me to post or submit at dgca after i showed him all my test results. Thus he filled the form CA 35 and gave it to me immediately, whereas DGCA class 2 documents were given to me by him in a large envelope which i posted to DGCA thus got my medical by dgca from post in the following weeks.
Go to your class 2 medical doc and ask him for the form 35 as he's supposed to give it to you. The medical will come from DGCA if your doc has posted or sent the documents to the DGCA Medical Office. I don't think the process for renewal is any different. Just take your receipt as that's the only proof you have.