New day, new thoughts, I was able to make it work!
The whole problem was within the Serial.read speed.
Here's a topic about the problem:http://forum.arduino.cc/index.php/topic,48103.0.html
Only if I add "delay(1)" to the loop, I'm able to send the packet as a whole!
Also, when I read the message, I need to add delay(1), or else the message is getting randomly corrupted.
!NOTE! If you add delay to receiving, buffer might fill out faster than you can read the characters, so everything longer than 64 characters will get cut.
Solution: remove the delay if possible or increase buffer size to 128 or 256(very high, takes away from SRAM).
It was about that little thing all the time. I was so sure that it should work with that code that it made me insane. It just needed some extra time.
If anyone knows a better workaround for this, please let us know. Delaying is never a good option, but in my case, I don't need super lightning fast transmissions.
I hope someone finds this solution helpful.