Those periods of 14 days are actually server based and not starting from the time each user registered.
This means that the next period will be at 8/1/2017 17:53:20 regardless of when you registered.
I was registered last June 12, 2017.
Doesn't matter because you made all your 77 posts in the same "period of 2 weeks". You will need to post at least once in the next period to increase your potential max activity to 28.
Btw, please stop spamming to increase your post count.