How do you know that you have gender dysphoria please help?

If you think you may be gender dysphoric, get to a therapist who has experience with gender dysphoria: ask your MD for a reference or list of therapists who might help or could point you to the nearest therapist with experience there. A lay person cannot tell you you have GID: it's a medical diagnosis. If you have memories of telling people you are the opposite sex from when you were little, if you never did what people expected you to do based on your physical sex: didn't like sports, wanted talk more than play physically, changed your appearance often from a young age, to appear to be the opposite sex, ... you MAY have GID.. the only way to know and get help is talk to a trained professional who has treated GID AND who doesn't include things to the effect of "can be cured" or "we can fix that .." or .. "can change."

MOST often a person doesn not have GID and just needs help to understand what they are and help to become what they want to become. True GID is extremely rare (1 in 2000 to 5000 persons in the US actually has GID.) Get experienced professional help whatever happens: it will help you. When you speak to the therapist ask for the names of other patients who have agreed to be contacted and talk to them: almost everyone being treated wants to help, not cure.