How do you know if you have bronchitis?

I have been coughing for half a year and it produced thick phlegm. I do not smoke, I eat healthily and exercise, but I had a build up of colds and allergic reactions and for a half a year I haven't been able to get rid of it. I tried antibiotics, but they just haven't worked. The symptoms of bronchitis sound like what I have, but is there any other thing I could have? What are some ways that I could get rid of it without antibiotics, because they just don't work. All answers appreciated.