These insecure feelings are not only for beginner riders. I am 38, got my first pony at 4. But I sold my last horse at 27 and moved. During the time frame that I did not own horses I would ride friend's horses. My ex-husband was a team roper, so there were always roping horses to ride especially when friend's were on the rode rodeoing. So I got to continue riding and caring for horses. Then I did not ride for about 3, nearly 4 years as the marriage fell apart. Now I have recently gotten horses again. The mare I bought for myself is awesome, but she is not quite 5 and her training particularly on trails and on the ground is lacking. I found myself nearly paralyzed with fear and feeling ultra insecure about my handling and riding of horses. I know how to handle these misbehaviors, but if you look at my posts you see me asking for tons of advice. The advice I get is great, and although it mostly reassures what I already know it builds my confidence to hear that others would handle things in a similar way. And if I get a new great idea then that's even better.
My point is please do not feel like you are alone in feeling insecure or unsure of your work with horses and that it is only because you are behind the learning curve. I can only speak for myself, but I think that all of us that love and work with horses second guess ourselves and overthink sometimes. I know that I overthink all of the time, about literally everything, but that when I'm actually on the horse I mostly just do. I think you are approaching everything wonderfully by learning everything you can because then you just know what to do and it happens naturally without the overthinking portion.
Keep going! I am excited to hear about your journey.
to ride on a horse, is to fly without wings