It sounds like you were breaking the rules on several fronts.
According to the FIDE Laws of Chess:
6.2.3 A player must press his clock with the same hand with which he made his move. It is forbidden for a player to keep his finger on the
clock or to ‘hover’ over it.
You would probably be punished under the illegal move rules:
7.5.2 If the player has moved a pawn to the furthest distant rank, pressed the clock, but not replaced the pawn with a new piece, the
move is illegal. The pawn shall be replaced by a queen of the same
colour as the pawn.
7.5.3 If the player presses the clock without making a move, it shall be considered and penalized as if an illegal move.
7.5.4 If a player uses two hands to make a single move (for example in case of castling, capturing or promotion) and pressed the clock, it
shall be considered and penalized as if an illegal move.
7.5.5 After the action taken under Article 7.5.1, 7.5.2, 7.5.3 or 7.5.4 for the first completed illegal move by a player, the arbiter shall give two minutes extra time to his opponent; for the second
completed illegal move by the same player the arbiter shall declare
the game lost by this player. However, the game is drawn if the
position is such that the opponent cannot checkmate the player’s king
by any possible series of legal moves.
It sounds like you were either moving with one hand and pressing the clock - 6.2.3 or using two hands to make the move - 7.5.4