Two-hand forehand? I would seriously not recommend using that... No reach, and IMO one-hand allows way more power and in the end result, control. JM Gambill proves that two-hand forehand is weaker than one-hand.
Now back to your problem. How old are you? Because at the junior level, I don't see many super topspin players, and the ones that do punch a lot of topspin, usually don't put much pace. And I don't see how slicing a heavily topspin ball is hard, because it is already spinning the way you want it, all you need to do is block it back.
Heck, today I played someone who hit really deep heavily topspin shots. I attacked his backhand first of all since that side is harder to generate massive topspin and I hit his balls on the rise (it can be hard to time from pace and spin, but after a while you should get used to it). I also found that attacking the net was sometimes a good idea, but only when he was hitting the ball on the run. If I basically gave him the ball and went to the net, he would hit it over me with a load of topspin, giving me no chance to go back and return.
Thanks for the advice. Maybe I had a bad day on slicing the ball. Next time I´ll try to hit his balls on the rise as you said, trying to put some spin on it because is very difficult to flatten this kind of balls. If the ball is getting too high I´ll try to slice better this time. Everything but trying to be defensive (I´m much more comfortable on the attack than on defense). And yes, you´re right, he generated less topspin with his backhand. And he had a flat serve too. That´s how I managed to beat him the last time.
About my two-handed forehand, everybody tells me the same thing. But I have played like this for the last 12 years and I´m not going to change now. It´s an extremely natural strike for me, very consistent even if it´s quite flat. Of course there is the reaching problem. But, when I cannot reach the ball I hit a one-handed forehand without problems (I always use a single-handed forehand on the run).
This is a piece of an interview to Fabrice Santoro:
I notice that you hit with a double-handed stroke on both your forehand and backhand. Why and how did you decide to utilize the double-handed stroke rather than the single-handed one?
Joachim Gay (Singapore)
When I first picked up a racquet when I was six years old it was the same weight as the racquet I use today. It was far too heavy for me so picked it up with two hands. Had I started playing with one of the children’s racquets that you can buy today I probably would have played with one hand. And I probably wouldn’t be on the tour!