Confused about how much cardio i should be doing

hi have recently just moved to a new gym and my new instructor is confusing me , i have already lost nearly 2 stone, and i enjoy doing cardio but my instructor has said i should go for higher level and less time, i have been told and read that to lose weight you should burn fat so i therefore try to do quiet a bit of cardio, i also use weights and feel that i have been losing inches but my weight is staying the same and its really annoying as at my previous gym i was losing a bit of weight and my instructor there encouraged me to do as much cardio as i felt i could , so just looking for some advice as to how much cardio i should be doing

Three times a week I do 20 min HITT (High Intensaty training) runs its the best for burning fat and three times a week I do weights for an hour.