How can i know that im into girls ?

You can try to analyze your feelings and sensations about boys and girls. Maybe you can imagine yourself with different people and be as honest with yourself as you can about your emotional and physical responses to those fantasies. Whatever makes you feel good and happy determines who you are attracted to and consequently what your orientation is.

I believe that you need to explore your personal feelings. How does it make you feel when you think about girls compared to boys. Do you like both? Maybe you just need to explore these feelings in order to know what you really like or want. I believe that talking to someone that won't give advice but help you may also be another avenue to explore. Maybe contact someone within the LGBTQ community who understands mixed feelings is another option. Would talking to your parents help, if not that's ok. There may be another family member or friend you can trust just to talk to until you decide what venue you wish to take. There are many options and resources available, it's just knowing where to find them or who to talk to. I think once you have a chance to talk or experience some of these options you'll know what works for you.