Beautiful horse! I can understand why you are nervous, but it sounds like you are in a perfect position for ownership. Being surrounded by experienced and knowledgeable people who will help you is a very good start. It kind of sounds like to me as if you are a perfectionist, and you want the very best for your future horse. I think that is good that you do not jump into things without a lot of thought. It takes a very long time to become an expert in any thing, but you have to start somewhere. :) You will learn, and as you work with horses more, you will increase your knowledge and gain a vast amount of experience. Do not compare yourself to others, but be the best that you can be! Take the other horse owner's advice, listen to your trainer, and try to use that information. As time goes on, you will be a very good rider.
If you look for truth, you may find comfort in the end; if you look for comfort, you will not get either comfort or truth; only soft soap and wishful thinking to begin, and in the end, despair. -C.S. Lewis