To figure it out, you need to trust what you feel toward women. Learning to listen, and trust what you feel are abilities that will help you discover your sexual orientation. Here is a definition that could guide you: A lesbian is a woman who feels attracted physically and/or emotionally to other women. This identity also includes non-binary people as some non-binary people will identify as lesbians.
We need different amounts of time to figure it out. Each person has their own discovering pace when it comes to their sexual orientation. Some will know very quickly and others will need time. Sometimes we know simply based on what we feel in the presence of other women or through media representation and sometimes we need to make sure through concrete experiences. The answer will come from you, and those who pretend to know for you are wrong; only you can confirm it.