First off, Im did not question anyones credibility, nor am I trying to increase mine. Fans and coaches (even myself on occasion) disagree with calls all during games that quite honestly we have no clue what could really be going on. There is ONLY 1 angle that an offsides can be correctly called from. Im sure that there were a few people who may have been on line with that call. However, the claim that you, another knowledgable referee, and some other person were EXACTLY on the line I find very hard to believe. Who knows, maybe you were, I'm sure Tullahoma parents on the opposite end of the field felt that they knew 100% that she was offsides, and they have no clue. The press box may also have a great view of the field, but unless the offsides call is made exactly at half field, they have no idea.
Also, if a player receives the ball 4 yards behind a defense in front of the goal, this could be the result of a failed attempt at an offsides trap perhaps? Many possibilities. The referees, although not perfect, miss ALOT less calls than the fans and coaches think.