Hiya! Congratulations on your success so far!

I just thought I'd mention an alternative to squats that I do when my knees are rice krispies. Sit on the very corner of a chair, feet flat on the floor, legs apart. Shift your weight forward to your feet as if you're getting up, until your butt is slightly off the chair. Hold for a few seconds, then sit your butt back on the chair. Lather, rinse, repeat.