I am beginning to think that I should have started my trip in another city as it appears difficult for train travel from Barcelona to Nice. Any ideas?
According to the timetables at www.bahn.de, starting later this month there will be one daytime route (Barcelona Franca-Montpellier-Nice) that will take 10 1/2 hours and has only the one connection.
Or you could fly on Vueling, a budget airline. Book ASAP to get the lowest fare. Pay attention to luggage size and weight limits and especially to the check-in deadline. On budget airlines if you don't have a boarding pass in hand when that deadline arrives, your ticket is worthless.