Hi Lisa!
Thanks so much for your help....
I am ashamed to say I didn't know what a glute-bridge or clamshell was...
At least not by name...I just looked them up tho...and they definitely look like things I can do!
I used to do a little bit of the stepper machine...but I stopped because it bothered my knees...I am assuming because of the push off from my toes...never thought about that! The low step ups are something I can definitely try...concentrating on keeping my feet flat tho and pushing through the heel like you say...more like what I do with my squats I guess. I used to do step ups on the bench before my knees went, I just assumed these would be bad...but I guess I was wrong!
I am willing to do anything to strengthen whatever I can so I can take some pressure off of the knees!