I have some tips! :) 

I think you in general need to accelerate more with the forearm to generate more spin. 

At backspin you want to have an explosive and fast motion with the forearm, to be able to get the ball over the net. The reason you put the ball in the net sometimes is a too slow motion, i also think you will have some problems if get more backspin against yourself and not get the ball over the net, but maybe then you will accelerate more. 

Accelerate with the forearm is not as important against topspin, since it is already spin in the ball but i still think you should try to accelerate more with the forearm. You loop out some balls with should suggest to little spin in the ball, spin in the ball makes the ball go down or that you need to loop more forward. 

More acceleration=more spin=a much more safe game. Spin make the game alot of safer. In example Timo Boll is very safe since he always loop with the spin and the spin makes the ball go in an arch and go down and not out. 

Good luck! :)