I Have Lots On My Mind

I am currently an in-home and business-to-business designer. I've never done this kind of work before. I have a Bachelor's of Science degree in Interior Design and a Masters in Business Administration degree as well. Working on 100% commission felt very risky, but I have done network marketing in the past and am a firm believer in opportunities that are high-risk, high-reward. I'm doing pretty decent at my current career at the moment, but I'm not a "sales-y" person. I never have been. I've done customer service my whole life and have found that people buy from me because they like and trust me. Surprisingly I have had a very high close-rate more months than few. But I've been running into A LOT OF client issues lately. Something goes wrong during installation, clients wanting to change the design, clients complaining about wanting more of a discount. It ALL annoys me and gets me upset. One thing I've learned about owning your own business is that you are working ALL the time. I fully understand that hard work pays off, but lately I don't feel like it's paying off for me. Lately I feel more upset than happy. I want to be successful at this, but I don't know how to ease my frustrations. I'm trying to enjoy my successes at not let the negative moments "get to me". I don't know what to do. I think I need to work on becoming better at this job.