Hey, Roxie !
What are you doing for strength training ? If you're not engaged in any type of strength training, I'm going to encourage you to start with one dedicated workout per week. a good strength training program will help increase your lean muscle. Having more lean muscle will help increase your metabolism by making your body more efficient at burning fat. Also, having more lean muscle will help tighten you up.
And along with any strength training you do, you should consider some cross training. Zumba is great. I love it, but consider trying a spinning class or maybe kickboxing. cross training will help keep you from getting injured.
You don't have your food diary posted. So, I don't know how much or what you've been eating. I know this is going to sound strange, but the reason you may not be losing is because you're not eating enough. Women are notorious for increasing the amount of exercise they do and decreasing the amount they eat. This is no good. If you want to lose weight, you need to eat. The quality of the food you eat matters.
Also, if you find yourself getting bored with your Zumba routine, then it's time to change your routine. Do you have other Zumba instructors at the gym ? Take their classes to see what they do. It's a way to learn some new moves that you can forward on to your class. I learn from other instructors all the time. When is the last time you went to a fitness conference ? I try to go to conferences once a year. Conferences are how you learn new moves and techniques. So, you might want to see what fitness conferences are in your area.
You may even want to ask all the Zumba instructors to get together to have a brainstorming session. trade music, trade moves. it's another way to change up your routine.