Looks like you had fun Sarah.
My suggestion, if you want to get into Jumping or Eventing, is to find a Coach who is not only very experienced in the sport, but also rides it, trains it and is up to their necks in it. Someone who is at Prelim or higher *someone who has ridden that level, or is currently riding at that level*
Obviously, you'll need proper tack, but you know that :) It is hard to give you constructive critisism when you are in tack that does not encourage nor incorporate proper jumping form. For example, you're in a dressage position instead of in a functional 3 point seat and yadda yadda yadda. So it isn't fair to say what you aren't doing, when your tack isn't aiding you to do what you should of been doing.
Being that both you and your horse are beginners to this, you should be doing alot of flat work in jumping position, learning how to solidify your lower leg, activate your core and just remain with Majic, and then incorporating that over trot poles and xrails.
Learning how to keep your legs under you, wrapped around his girth, learning a functional 3 point, how to stay over his center of gravity, how to use your core every step you and your horse take, how to release and so on and so on.
I would be encouraging you to do GAG before BN.
Looks like you had a great time, and you did a great job for your first time! Congrats for your accomplishments!