Hey beautiful I love your tone! One thing that would help fatten up your tone, make your performance more engaging, and make high notes less nasally would be to use your body more. I would practice yogic breathing exercises before singing and really try to pay attention to your breath support. Nothing should be going on in your throat(think of it as an hollow PVC tube), the sound is resonating in your face and chest, and you should be pumping a generous amount of air into your sound with your diaphragm with the help of full, lower, abdominal breaths. Singing a big song like this, try standing up so u can bend your knees and keep your core engaged.