When i render it cuts a few frames for no reason (ok it doesnt make sense so just read the post)

I  think you are confusing what you are seeing in the timeline. The Current Time indicator sits at the beginning of the next frame. If you go to the last frame of a comp that is 6:14 long the time display will be 6:13 because frame 6:13 has not played yet. If you rendered that movie and went to the end of the last frame the time would be 6:14 because the last frame would be over and you would be starting at the next frame. 

This is different than when you make a cut in an NLE like Premiere Pro or Final Cut, or Avid. The cut happens on the frame so do not see anything when the time indicator is sent to the out point. After Effects is not rendering the wrong number of frames, you are just not understanding the time display.

Is your work area (the bar across the top) extended out all the way both at start and at the end before export? You may be missing a frame or two at the start?  🤔 🤔