In addition to the suggestions already given, give bench step-ups a try. With the bad knee, use a shorter step until that leg becomes stronger. It's a simple move. Start on the ground and step up. Or start on top of the step and step down. 12 to 16 reps per side for 2 or 3 sets is plenty. That targets that little area between butt cheek and top of thigh. That's the famous "fanny lifter" move from the Firm workouts. Stepping off to the side will target the inner thigh and quads.
They use a 14" step but with a bad knee, use lower and build up to it. They also add weights (dumbbells on shoulders or held in hand) to challenge you even more. They also don't do the sets back to back. You might do one set then go work a different body part, come back for another set, then go do something else sort of thing.
Hurt one of my knees almost a year ago, took a long time to build back up to using the 14" step and I did it the same way I'm suggesting to you. Start lower and build up to higher. Running never hurt the knee but deep squats and this move on the step sure did
My hat is certainly off to you for the amount of activity you're doing. You're looking fantastic, Hanna.