Don't think nutrition first, activity levels second. You will get your best success if you do both at the same time. Maybe add some additional upper body exercise (think wall pushups, dumbbells) since you're doing a fair bit of lower body stuff with walking and stair climbing.
Your eating plan seems good but work on easing back on the two snacks over the next week or so. Some people also find they have sensitivities to peppers and tomatoes (nightshade family) so if you have issues you might want to cut those back as well.