Hello Mandy and welcome to the forum.
However many times per week you want to do weights is fine provided you make sure your muscles are getting at least one rest day in between. Pump is a pretty intense class but your body could still get too used to it. Have you increased the load since you started? You should be progressively taking the load up. Talk to the instructor of the class to get an idea of what and when. Personally I do weights twice a week for 30 mins although I would prefer 3 times as I think 2 is a bit conservative but I never seem to make it.
As for cardio this is the real fat burner not the weights. The weights assists in fat loss in an indirect manner due to muscle using more calories to work than fat does, therefore, the more muscle you have the more energy you will burn even at rest. If you are keen on using cardio for weight loss you really want to be doing a minimum of 4 sessions per week at a minimum of 30 mins. Maybe change some of your pump classes for combat or attack instead. But again maybe discuss with the instructors of those classes. I do at least 5 sessions per week at 40 mins plus.
I have read (not sure how accurate this is) that you can't really build muscle whilst doing weight loss as you need to be increasing your energy intake to build it and weight loss is usually around decreasing your energy intake (calories). What the weights do for you during weight loss is help you to maintain the muscle you have. The reason you look more muscular is the fat that has been lost from those areas allow the muscle to show through or be more defined. Is it possible you are confusing your body by trying to do two things at once ie. build muscle and lose fat? Just a thought.
Oh dear I have gone on a bit. Anyway apart from all that I think it is fantastic that you have the motivation to exercise as much as you do. I feel you need to find the right balance that will help your body head towards the goals you have but you motivation is awesome to be doing what you are. So big pat on the back for that alone and your body will be loving everything your doing for it.
Sing out if you would like any more info.
I wish you all the best on your weight loss journey.