Is this age difference bad?

No the age isn't huge. As long as you are on the same page then all is good. I know people who are 19 years apart. Its not a matter of age. When you were younger maybe because he had more 'life' experiance but that doesnt mean that you werent supposed to be together. And if you have been together all this time obviously something is right. :) Dont worry about what people say. They dont know you or your life so just enjoy what you have.