Well I'd say it depends on what you care for. Personally I like to be able to pull the foreskin allll the way back, fully unfolded, without the head being pulled down at all, but plenty of guys have no problem having a shorter frenulum.
I'm amazed that you were able to stretch yours that much though. How did you do it?
I thought that the head should not be bent when the foreskin is retracted all the way back. Seems it is not a must? Wonder how does the glans able to slide in smoothly if it is bent halfway during sexual intercourse? Wouldn't a bent glans interfere with sexual intercourse?
For frenulum stretching, I was 18 or 19 back then, I followed few exercise methods from a forum few years ago. It had pictures in it detailing the steps, I will try to post it here if possible. One of the exercises involve retracting your foreskin all the way back. Grip the retracted foreskin at its base pull it towards the base. By using your other hand, make a 'V' using your index and middle finger, place it firmly under your glans with the frenulum in between those two fingers and pull it outward.
Another technique, while having the foreskin over the glans, try to insert one or two fingers into the foreskin to stretch out its opening. Gradually work your way up to 3-4 fingers.
In the beginning it did hurt and sometimes the frenulum will get bruised and bloody, but it gets slightly longer each time it heals. I used these two exercises only for 1 or 2 months so I would say natural foreskin growth with age could also be a factor here. Will try to post the steps with pictures I could find it.