Kassel Forum: Transfer time at Fulda, from Frankfurt to Kassel

I will travel from Frankfurt Airport to Kassel by train (IC) with a transfer at Fulda Station. I have only 5 minutes to transfer from one to another train (from platform 6 to platform 3). Do you have any idea if it is enough time to do this transfer? I will be carrying my own luggage. Is there a possibility to the first train be late? If I lost the train, can I take another one with the same ticket? I will buy my tickets (return) directly from the DB site in the internet. Thank you very much!!!!