Ditto on the arms.
Also, I'd suggest closing your fingers, you're holding the reins very loosely. This is a big problem for me, too! All 4 fingers should touch your palm, which (mostly in the last few pictures, I'm pretty sure your 1st picture is a repeat), they aren't doing. This will help you give more subtle and accurate aids, and if the horse decides to bolt/spook, the reins won't be ripped from your hands. Which has, by the way, happened to me before. More than once.
I really, really like your shirt by the way! Haha.