Agreed with the others. My trainer periodically throughout my lessons will make me "give" my inside rein up completely. If the horse continues with the bend, I am doing it correctly. If it falls apart when I give my inside rein, I am riding too much with my hands. Dressage comes from the legs and hind end. And yes it is hard. I have a dressage horse that is very very difficult to ride. I used to ride like you, lots of hands, and preventing his natural "swing", my hands would even hurt after lessons. Now that I have learned more dressage and learned the correct way, I need spurs to ride him and my hands are very light. I've now learned that he requies ALOT of leg, even though he is a very hot horse. It is hard so don't try to make excuses, no one is getting on to you about it, simply pointed it out. You can't learn if you don't know what you are doing wrong. It took me over a year to learn to ride my horse.
When your riding him dressage, and you feel like you have a nice, correct bend, you can do a check. Briefly put your hands forward and give the reins a little, making the reins a little slack. If your horse continues on with the bend or reaches down for that contact again, you are doing it correctly, if he does not keep the bend, you are riding with too much hands and not enough leg.