Originally Posted by Goldorak

definitely do this and, as said by other posters, there is a very easy solution to your problem : just connect in CDG, and so fly LOS-CDG-JFK.
I don't know who booked you with a change of airport in Paris while there are plenty of CDG-JFK flights, but that was a big mistake. So even if you have to pay a change fee and a fare difference, that's an easy decision to take if you want to be in the US on your planned date.