If you are feeling slippery in the saddle then you either need to clean your saddle more frequently or breaks it in more . Or you need full seat breeches . And as for you not being able to move so much in your show coat , that’s normal I used to have that problem in the hunter ring but I grew out of that jacket and had to purchase a jumper show coat because I’ve switched over to that . And I got a size up from what I fit in at the time and I tell you it fits perfect and I have a lot of room ! Also try a breathable show shirt like Ariat makes really good ones ! And for really good full serf breeches with the knee patches try tailored sportsman !!