How do I know if I am transgender?

just listen to yourself and focus on what your heart wants. you may be experiencing some gender dysphoria so if you feel like you assigned gender parts (brest,genitals, hips muscles etc) dont fit what your brain is telling you what should be there

The best advice I have got is to experiment. Don't experiment in your head or in private because even though it's safe, your mind is a very powerful tool. Try and find supportive friends or family and test out names and pronouns, and try living as your identified gender (even if you're still questioning). Even if you come out to friends or family and you realize this isn't right it's a lot easier to tell them "I don't feel like x, but I feel more like y". It's a lot easier to verbally communicate and experiment rather than to medically experiment, and it's easily reversible. You don't have to know as a child, or know within a few months. Take your time with things and experiment. No one can tell you what you are or what you are not. Start by socially transitioning, see how it feels, and go from there. I recommend everyone who's questioning to always start by socially transitioning because you don't want to do any sort of medical transitioning as it's a lot harder to reverse if you are not sure.