I agree with everything that has been said thus far. I'd like to add, that it is important to know your hair.
I'm not a frequent trimmer, but only because I know the growth pattern of my hair. If I were to trim each time my hair appeared uneven, then I would be trimming growth and not bad ends. I've learned over time that my hair grows in certain areas first before the rest of it catches up. Sometimes that faster growth is 1 1/2 - 2" longer than the bulk of my hair that hasn't started the same growth cycle yet. It does all catch up and become almost even over a period of 3 to 6 months.
Trimming is important, but is not always the answer to uneven ends. It is important to inspect your ends to determine whether they are split, frizzy, or uneven. What you decide to do about ends should be based on which of those conditions exists.
If they are split, you have to make a judgement on whether you want to try to baby them for the sake of lenght, or cut them. If they are just frizzy but not split, then you need to step up your conditioning, moisture, and protection. If they are uneven but healthy, then you have to decide whether you want to wait on your hair growth cycle or just trim the longer ends. Whatever you decide, it just takes time and patience. Unfortunately, there are no secrects or quick fixes to achieving full healthy ends.