So I am leasing a horse for the summer and she is absolutely amazing and I love riding her. My mom came out with me today and took some pictures and I was surprised to see that I have a chair seat in a lot of my pictures. I was wondering if anyone can tell me what I can do about it. I usually have a very good position, but I think my bad position is a combination of a big saddle ($200 ebay stubben that turned out to be an 18" and not a 17", but it is VERY comfortable and doesn't feel wrong at all) and the fact that I need to work on her brakes more so sometimes I was bracing against her to slow her down/stop her. She is 20 years old but you would never know it, I still can't believe it based on how she looks and how much energy she has. Also I think my stirrups are a little long even though they feel fine to me, which worries me.
Any tips? Thank you very much in advance :)