I'm so annoyed at being misunderstood. is something wrong with me mentally?

Mentally, maybe no: Emotionally maybe yes. Much depends on how you actually feel misunderstood and how much insight you have into the problem. Without knowing what bothers you an answer is guess work. Write down what annoys you and rate it from 1 to 10 or put them in order of importance, most severe to least severe. That could be a good start to solving it. Most likely very little is worth the worry. Counseling?

Annoyance: Being misunderstood is an experience most humans have at times -- some of us quite frequently. And the wish to have others understand us is natural. Some are more sensitive to this issue than others though. If being misunderstood triggers intense reactions that last for hours or days, you probably do have a problem. A therapist or psychiatrist may understand and be able to help.