How long should it take for me to loose 20 pounds?

I'm 5'4" 135 pounds... I used to be a swimmer and was 115...but I quit for a year and well got bigger... I'm now doing 2 a days workouts... my last one was the fallowing: 30 min run, 10 min bike, 10 min core (saxon side bends, 200 sit ups) then 10 min cool down (bike and run). And as far as diet i do weight wachers.....and only eat 25 points a day....(i'm allowed 29 with 45 flex)