Okay most of these photos are quite frankly useless to critique from so I'm only going to use one.
For starters, you've only had four lessons, and you LOOK like you've only had four lessons. Whoever keeps telling you you're a natural doesn't know what they're talking about. You are a beginner rider. You have faults. Lots of them. Your position is not balanced and is not healthy for you OR the horses you ride.
You need a LOT more lessons.
I'm not saying this to be mean. I was told I was a natural too. It made me complacent and lazy for YEARS before I opened my eyes and actually looked at myself for what I really am. You remind me of myself, right about four years ago, except I'd had a heck of a lot more than four lessons. I simply HAD NOT IMPROVED because my instructors kept telling me I was a natural and I was complacent. I didn't think I needed to improve.
I didn't think I needed to improve at all for YEARS. Not until I got my eventer. The number of times he ran off with me, bucked, bolted... he really opened my eyes.
Don't become me.
Now onto the real critique. Your heels are down, but you're forcing them down, resulting in your entire leg shooting forward. I do this too. It's a hard habit to break. Just let your leg hug your horse. It should be relaxed. Strong, yes, but relaxed. Tension is bad. Your butt is way back at the very back of the saddle, which puts an incredible amount of pressure in a very small area that isn't really designed for weight carrying [no part of the horse truly is so one must ALWAYS be aware of where one's weight is]. You are, as a result, leaning forward to keep your balance.
I think the only thing I can really comment on being GOOD here is the line from your elbow to the bit. Perfectly straight, which is absolutely fantastic. You don't have my worst habit. I carry my hands very low and stiff and I'm STILL working on breaking that habit nearly three years after realizing I have it.
I've drawn lines on your photo demonstrating what I see. And I've drawn lines on a photo of a dressage rider that I found with a quick google search. Her lower leg is a little farther back than is classically ideal but that's because she's giving an aid to her horse in that specific spot. They put the aid for piaffe back there so that it's basically impossible to accidentally give it.
Since you are riding on the flat, not over fences, you should be aspiring to a perfect ear-shoulder-elbow-hip-heel line. When you're jumping your position on the flat is a little different but we're not addressing that now.
MAKORA THOROUGHBRED SPORTHORSES