Thank you for reaching out to us, I am happy to assist with your question.
According to the information you have provided, I would recommend that you haveTackiness Chop on your backhand along with Flextra on your forehand or a long pip rubber.
To have a better feeling of controlling the ball, Tackiness Chop can create heavy underspin against a variety of shots. It produces much greater spin than Flextra. With Anti-Spin or Long Pips on the other side, it can generate quite favorable results.
Feint Soft is a standard long pips-out rubber that is outstanding for chopping against topspin drives. The long pips will send your opponent’s spin back to them. Usually used in combination with a high spin inverted rubber to force errors from the opponent.
Flextra, which you are currently using is perfect for the beginning player and those who like to vary the speed and spin as a defensive player.
Hope you find the answer is helpful!