I do not want to put on any more size to my thighs, what are some things I can do to still strengthen but not bulk up?
Avoid doing squats, and stick to long-duration cardio and resistance training.
lunges and hip thrusters. Don't eat carbs after your workout, and try to reduce carb intake over all.
If you do squats, do them as body weight with biggest range of motion possible - ass to grass and knees up in the deepest squat position.