I agree with the previous posters....we ALL get discouraged at times!!! It seems like you're going through a tough time anyway...and you're focusing on a competition goal to boot. I would focus on bonding first, especially where the mare is new to you. Go for walks with her, sit in the grass and watch her graze, take her for a laid-back trail ride. I'm not saying don't do barrels too, but don't make it your only focus--it sounds stressful! Be careful too, about making her barrel sour. If you're doing the patterns over and over and over and getting frustrated, she's probably frustrated too. Try to end on a good note, then go do something else with her. Good luck!
I have spent some time riding her in the pasture and groom her everyday. I'm planning a trail ride next week with a friend of mine. We just haven't gotten it together yet! She's always trying to test me because I swear she knows I'm not experienced. I make a HUGE point to never get frustrated with my horses, in events I never believe it's their fault they are both seasoned professionals, haha, I just get frustrated with my self for making small mistakes. My Aunt always makes me end on a good note, then we go for a nice walk and a rinse off.