I am new to chess so your legal/illegal pawn move is beyond me to debate. However, my hubby suggested the following site. I copied over the Movement rules. On the site one can search and ask questions.
Does this help?
Pawns can only move forward. When a pawn makes a non-capturing move, it goes one square forwards. When a pawn is still on its original square on the second row, it can make a non-capturing move forwards of one or of two squares - if it moves two squares, the first square must be empty. A pawn captures one square diagonally forwards. When a pawn has moved two squares forwards, the opponent has the possibility to take it en passant: in the directly following turn a pawn of the opponent may take it also on the square that was passed by. When a pawn reaches a promotion square, that is, a square on the last row of the board at the opponents side, it promotes. The owner of the pawn may decide to which piece the pawn promotes. In standard chess, this is a queen, rook, knight, or bishop of the same color as the pawn. It is possible to promote to a piece that is not lost, so for instance, by promotion, a player could have two or more queens on the board in standard chess. In chess variants, and fairy chess problems, the most used and recommended rule is to allow promotion to any type of non-royal piece that was on the board at the start of the game (i.e., no promotion to king, unless specified otherwise). Promotion is still to a piece of the same color.
A Pawn moves without capturing by stepping straight forward one space, and it captures by moving diagonally forward one space. The most accurate adaptation of the Pawn's movement on a hexagonal board comes from McCooey's Hexagonal Chess. This is diagrammed on the right. In Glinski's Hexagonal Chess, the Pawn captures orthogonally forward on the slanting rows, and Glinski incorrectly describes this as diagonal movement.Squares where the pawn can move to without taking are marked with a green circle; squares where the pawn can move to with taking are marked with a red circle in the left diagram, and with a red X in the right diagram. 
For more information on how the Pawn moves in modern Chess, such as capturing by en passant, see our Illustrated rules of chess or the FIDE laws of chess.
The Pawn is a divergent piece. This means that its capturing moves and its non-capturing moves are not the same. In the Pawn's case, it captures one space diagonally forward, and it moves without capturing one space vertically forward. The Pawn is the only divergent piece is regular Chess. The other pieces capture and move in the same way. But other divergent pieces are sometimes used in other variants. A few of these divergent pieces include the Berolina Pawn, the Murray Lion, and the Cannon.
FIDE Laws of Chess
5.6 The Pawn.(a)The pawn may move only forward [except as limited by Article 4.2].
4.2No piece, except the rook when castling (Article 5.1(b)) and the knight (Article 5.5), may cross a square occupied by another piece.
(b)Except when making a capture, it advances from its original square either one or two vacant squares along the file on which it is placed, and on subsequent moves it advances one vacant square along the file. When capturing, it advances one square along either of the diagonals on which it stands. (c)A pawn, attacking a square crossed by an opponent's pawn which has [just] been advanced two squares in one move from its original square, may capture this opponent's pawn as though the latter had been moved only one square. This capture may only be made in [immediate] reply to such an advance, and is called an "en passant" capture. (d)On reaching the last rank, a pawn must immediately be exchanged, as part of the same move, for [either] a queen, a rook, a bishop, or a knight, of the same colour as the pawn, at the player's choice and without taking into account the other pieces still remaining on the chessboard. This exchange of a pawn for another piece is called "promotion", and the effect of the promoted piece is immediate [and permanent!]. (e)In a competition, if a new piece required for the promotion is not immediately available, the player may stop his clock to ask for the assistance of the arbiter. The player must complete his move correctly, in the manner specified in Article 5.6(d).