Hi.
Only time will tell where your attractions will land and how deeply you will want to be involved with girls and/or boys. Just remember that you are under no deadline to figure it out. Sexuality is really a life-long exploration.
Many feel that sexual orientation is fluid, and that people's sexual and emotional attractions shift over time. For some, this shift may be drastic and for others almost imperceptible.
"Experimentation" is sure to give you important information, and so will your future relationships. As you date and spend time with people, try to stay open to your feelings and try not to judge yourself--whatever your attractions may be. Over time, you may drift toward girls or boys, or eventually decide that you would like to date both.
Give yourself time to explore. As your feelings for this particular friend evolve, use your intuition to figure out whether to act on them or not.
Meanwhile, it's great that you feel comfortable enough to share this with your mom. You're very lucky to have someone you can talk to honestly.
Best,