Perhaps you don't really need to lose weight; you may just need to spend less time in front of the PC and more time toning the muscles... I know that's part of my problem... When we don't exercise enough our muscles lose their tone, so even if we don't gain weight, we can look heavier.
You might look into doing some yoga, which really helps tone the muscles and makes you look taller and leaner.
Also, be sure to add some weight exercises to the walking, in order to build muscle, as muscle burns fat.
My weight is 130 for more than a year now and I used to look slimmer , I used to be more active but these last 3 months I m always sitting on front of PC , myBMR is 1351.