How do i get my horse's respect?

I have a beautiful APHA mare who I've been leasing for 7 months now and she literally does it all. Western pleasure, english pleasure, gaming, jumping, trails. EVERYTHING. But she's very marish and thinks she's the boss and thinks its okay to push me around. I have to ride with spurs and if those don't work then I ride with both a crop and spurs. She throws a fit at least twice everytime I ride. When I lunge her she only goes to a trot and if I try to make her go faster she pins her ears and has even kicked at me. But she can be a very good girl too. She's always happy to see me and walks right up to me when I go get her from the pasture. I just don't understand why she throws ***** fits all the time. I'm not afraid of her, I discipline her by making her turn the tightest circles possible or if she bucks she gets the whip. Please tell me what I'm doing wrong!!!! Her saddle fits, so don't say its that. I use a firm voice, go AH AH, everything. She just doesn't listen and doesn't care. I wanna show her but I'm not trying to embarrass myself by getting thrown off!