Hi Julia! Congrats on losing 50 pounds. That's wonderful.
As far as the last 7 to 10, well they are the stubborn ones that always resist change x( . The closer we get to our desired healthy body weight, the harder it is to lose those last few pounds.
First, as you already mentioned, is clean eating. This plays a huge role when we get down to the nitty gritty.
Second, is shocking your body with a new exercise routine that it is not used to so that your body is forced to adapt to a new form of activity.
Third, leaving your comfort zone. This falls along the same lines as shocking your body with a new form of exercise, but leaving your comfort zone can also be done by simply increasing your intensity or changing your exercise order.
You said you lift weights three times per day. Well, lets change that because your body is too used to that and lifting weights plays a huge role in losing body fat. So now lets lift weights two times per week and do total body workouts. Not forever, but just for now to make a change.
Then lets do cardio on the other days. We'll do cardio 4 times per week for 45 minutes and all different types. Try step aerobics, kickboxing, running, and biking (or another one that differs from those mentioned). After each cardio workout do 5 to 7 minutes of core work and stretch.
That should stimulate a change. Good luck!
Can you give me a general idea of how much cardio you do per week? thanks, Julia