What am I doing?

I am coming to the conclusion that I suck at my job. My success is based solely on the number of admissions I obtain on an average weekly basis. I should have 2-3 by this my 6th month. Unfortunately I average 1.4 and that is unacceptable. I also made a judgment call earlier in the week that got me a written warning from my boss. As a marketer for hospice, I generally am allowed to set my hours. Granted most days are typical 8-5, but some days it is 9-3 and other days it is 8am-9pm. On said day I had a personal dr's appointment that I assumed would last 1 hour. It lasted 2 and the boss called while I was in there. Next day, I receive a call asking me to be in the office at 4 to meet with the boss. When I get there "on time" like I am 99% of the time, I wait about 30 mins then the meeting starts. Long and short of it is I am not performing as expected, weekly meetings with the boss, and weekly rides to learn from another rep. What set me over the edge was my boss saying he had lost all trust in me.
Never have I done anything that I would think should lead to a lack of trust. My accounts are seen. I don't falsify documents or call logs. Seeing 8 accounts doesn't always take 8 hours. My accounts are close together, the majority of them are small offices that I can go right back and speak to the Dr. at.
At the end of the day. I think I am doing what I should be. I am asking the right questions to the right people, but not getting the same response as the other two marketers. WHY? Why do I suck at a job that I am passionate about. I love hospice. I feel fulfilled when patients are admitted and we can help them through this difficult time. I can't figure it out.