After trying to hit altissimo for over two years, I've finally figured it out! (besides the awkward fingering for G above the staff I knew).
I've been trying numerous fingerings and embouchures forever and tonight I don't know what happened: I tried something different and altissimo A came out! I was so excited, I didn't try to find my altissimo chart, so I printed out another one and was able to hit every note up to C4!
It's hard to explain, but to hit the notes, I had to curl my entire lip over my bottom teeth and kind of squeeze my air and breathe up. I hope you understand that.
This was definitely a turning point in my musical career: It was such a high and I am so encouraged to practice a lot before school starts more than ever.
I'd just thought I'd like to share because a lot of you have tried to help me with my altissimo woes.