Do I Wait or Do I Tell?

This is one of those sites where I am supposed to sit down and type up my own story, but my own story has barely begun because I am stuck. I know you are supposed to agree to being at least 18 years of age when posting on this site, but I am hoping that my story can be published anyway because I am someone that could definitely use advice.
I come from a single mother, who loves me to pieces. I have always known about how I come from an anonymous sperm donor too. That’s as far as it had always been up until recently. I came across the Donor Sibling Registry earlier this year and let me tell you, that site has flipped my entire world upside down. I used to be under the impression that my mother told me everything she could’ve about my creation and background, until I typed in my ID number and saw several half sibling postings consume my computer screen.
This of course was something I wasn’t worried about at first. I just laughed it off and thought, “Hey! It’s okay, she probably just didn’t know about all of these siblings either.” I stayed hypnotized by this idea for a few days, but then something changed. I began to have the idea that she had kept this kind of information from me. I typed her email into the box that popped up when I acted as if I was going to sign into an already existing account on the Donor Sibling Registry. My heart sank. She had an account, it had expired, but she had an account that was up long enough for her to acknowledge every single posting from every single one of my own half siblings. She didn’t post about me on the site, and that I can forgive; what I can’t bring myself to forgive is that she kept all of these siblings from me even though she has seemed so open with me from the start. But now I am scared to tell my mom absolutely any of this. I so desperately want to know these siblings. I so desperately want to meet them, contact them; but I cannot do any of this as a minor. I would need her. So can someone tell me if it is worth it to tell her I know all of this, or if it is better for me to wait two years and do this all on my own? (since at that time I can legally request contact from my father too and hope for the best). Please respond and let me know what you think I should do if you are reading this because I am really frazzled about this whole scenario.