Here is a story for you that shows how a positive attitude can mean everything....
About 4 years ago I worked for a chain store with a very rude client. He was so rude that some of the other technicians were afraid to wait on him. Mr. S would always complain when he came in to fill his wife's prescriptions. No matter how quickly his order was finished, it was never good enough. No matter how low his presciption prices were, he would complain about having to pay. And, no matter how kindly I treated him, he would always grumble back at me. But, I decided that Mr. S. was my special case and that no matter how much of an dingus he was, I was going to prove to myself that I could control myself and my outlook on life. So, we went on like this for about 8 months. Then, Mr. S. stopped coming in. The head pharmacist said good riddance and wrote him off. I never thought I would see him again. About 3 months after that he returned to our store. His wife, who he had been working so hard to care for at home, had been moved to a nursing home after he had been diagnosed with cancer and became unable to care for her. He told me that being diagnosed with cancer had made him feel so guilty. He felt guilty that he was no longer able to care for his wife. And, he felt guilty that he had treated people so badly during his life. Then he started crying. I was in shock. He told me that I was the only person who had always been kind to him in spite of how he acted, and that he had been thinking about that alot lately. He said that he decided that he wanted to change how he treated other people from then on, because I made him realize that not everyone in the world was lined up against him. And he did change. I had always thought before that even if people didn't appear to be influence by your attitude, they were influence on some level. Now I know that the little things can make a huge difference.
If you have only had one bad experience it should not be enough to put retail behind you. I once worked at a particular chain store and hated it (quit after 6 days). If that had been my first retail experience, I would not have wanted to go back. But, I had worked other places before so I knew this was not how it is supposed to be. There are alot of places where you can enjoy working in retail.
There are some retail horror stories. But most of those retail pharmacy tradgedies could have been prevented. People give you back what you give out. Being pleasant and helpful will prevent alot of issues. It may also take people who have had bad experiences awhile to realize that you are NOT just the same as the person who made them unhappy before.
I am not saying that in a family practice setting you could have avoided all instances of people getting cranky at you. You don't get the online billing in medical offices like you do in pharmacy. So, often the mishap has already happened by the time the bill comes around. Pharmacy personnel can be procative and avoid the unexpected post-service bill. And, a front desk person don't get the rewarding experience of helping people solve problems like retail pharmacists. There is alot more to retail pharmacy than responding to complaints. The fraction of time I spend on that stuff is minimal. I think the family practice front desk job is different enough from retail pharmacy that you could at least give retail another shot.