First of all, that horse is a gem! she is cute and responsive, and when you are better able to put her together , you are going to be amazed at how nicely she looks and feels. She is perfect for you!
You are a cute rider with a ton of potential. I can't wait to see you in a year!
your lower back is way too arched (pooched butt). this puts your seatbones pointing backward, and you want them in nuetral; pointing straight downward.
your hand will be quieter when you are stronger and more balanced over your feet (you are almost there) and , most importantly, utilizing your core. This is what you need to work on the most.
if you can get some lunge line lessons, where you don't hold the rein, but are only responsible for posting off of your own strength and balance, this will help ou to become stronger, like a martial artist who stands strong over his own core. no butt pouching there.
if you cant get lunge line lessons, try occasionally practically dropping the rien (riding on the buckle in one hand , like a cowboy) and see how different it feels.