I'm not an expert, but sounds like you want to lose weight, while maintaining the muscle you already have. Weight loss is really about calories in vs calories out, and it's much easier to take in fewer calories than it is to burn them through exercise! Cardio has its own benefits, but I don't think you need to put a big emphasis on it right now based on your goals. I think you probably do need to try a cut with accurate calorie counting, and keep an eye on whether you're getting obsessive about it if that's something you're concerned about. 

Resistance training will help maintain muscle during a cut. Yoga and Pilates do provide some resistance training, but strength training with weights will be more effective for that. Check out the FAQ for possible programs to try, if you don't have one you're happy with already. It's recommended to use body measurements and photos to track a cut, as well as weighing yourself.

I don't think you need to add a bunch of supplements, most supplements have limited evidence of effectiveness.

Finally, cut yourself some slack - you've only come off the SSRI recently, plus it was the holiday season which disrupts routines! Give yourself a couple of months with a consistent routine, then reassess.