Civic,My car Is leaking transmission fluid.

As I noticed, my car needed two new cv axles, both in front left and right. Everything was fine, everything ran perfectly fine. The day of that I changed my cv axles, i had to bang the passenger side cv axle with a mallet to take it out. I then inserted the new one. After that I was driving to school only to feel my transmission slip and my rpm not meeting up with my acceleration. We added oil and noticed it was leaking when I got back home from school. It only leaks when I drive the car. Not in park or off. We changed the seal but it still had no effect. Less of a leak yes but still leaking.