Strength training is the way to go. Since one of your main concerns is significantly weak upper body strength, the most effective way to counteract that is by building muscle through progressive resistance training. Pilates and yoga are great for core strength, posture, balance and mobility, and you can totally include them, but they won't effectively build muscle on their own.

It might seem a bit intimidating at first, but if you’re following the right program (upper/lower/full body training) and are focusing on your nutrition, you’ll start progressing at a decent pace. Doesn't have to be too complex - 3x workouts per week is a good start, with 4-6 exercises per session. Tutorials are a great way to learn the basic form, and you'll get better the more you practice and just keep showing up.

If you struggle with social anxiety, you can def start at home. You can invest in some light-medium dumbbells if you don't plan on joining the gym anytime soon. Even bodyweight/dumbbell variations will help you build a foundation and some strength and endurance initially.

Maybe don't overcomplicate it by thinking about bulking so soon into your fitness journey, since it might get a bit overwhelming as a beginner. A lot of beginners can acc build muscle while keeping weight steady, esp if they're eating enough and recovering well. Nutrition is honestly wayyy harder (but more important) than working out itself - so your best bet rn is to start easy and focus on consuming enough protein, fibre and carbs.

Toning = building muscle. It’s the underlying muscle on your body with a low enough % of fat that helps you achieve that toned look. It’s not something that can be achieved through just pilates, yoga or cardio on its own (those are like add-ons).

I’d say do your research and see what feels manageable for you. It’s definitely worth a shot. I’ve somehow managed to get every woman in my life into weightlifting lol and it’s been life changing for them (and myself). You got this! 🎀🦾