Wendy you are doing AWESOME!!
And esp. For the pace of your horse, he is a little speed trotter
My only suggestion would be to hold your hands up and a little closer together - I only say that because I used to hold mine that exact way too and my trainer told me to put them closer together! - Although with a cast on your arm, that may make things difficult right now!!
As for the balance issues and cast that you've had to deal with, I would NOT have been able to tell EITHER of those things in this video if you hadn't said anything
Nice job!!! (and PS I couldn't tell you were scared at ALL you looked very confident!)