I didn’t understand myself until later in life, after which I was made to understand it’s quite okay not to know and even question your gender identity. Your gender identity is valid no matter the situation.
Here are a few tips that will help you understand yourself better:
Get a journal and write how you feel regularly
Talk about to to someone you trust, might be a friend or even a relative
Learn about other trans people and what it entails. You can join LGBT groups, google, or read any material with helpful information
See a therapist or counselor associated with trans community
Hope this helps.