How is this provably fair? The server seed is not constant, the server seed hash is not constant... ]
Essentially these two factors are generated as the bet is made, it is likely that they can be generated to make it lose. You should rework your system. A true provability fair uses a server seed, client, and random. The client can alter the client seed, they can refresh the random, and the server stays constant *or at least changes at regular intervals* With the way its set up, I advise people to play with caution, I just miraculously lost all bets placed.