I’m going to make some assumptions here, in order to answer your question.
1) You are riding english, because most western bits are smooth, since most western bits are curb bits, which are automatically more severe than smooth-mouthed bits.
2) You are not riding dressage because only smooth-mouthed bits are legal for dressage.
3) That leaves hunter/jumper or pleasure riding, in English tack and some type of a snaffle bit.
The problem with your starting point, and I don’t think you are going to like my answer, is that anything other than a smooth mouthpiece (and I include in this category mullenmouth snaffles, jointed snaffles & double jointed snaffles) is designed to be at the minimum uncomfortable for the horse and possibly downright painful. This is an issue because, similar to a human wearing shoes that rub or pinch and develop blisters, calluses, etc on the affected foot, anything other than a smooth bit can develop what are effectively calluses on the the various parts of the horse’s moth so that he can no longer feel the bit correctly. It sounds to me that what you are dealing with is this loss of sensitivity to the bit. If you go to a more severe bit, it may work for a short time until the horse builds up new calluses to protect his mouth from the new bit, and moving to a still more severe bit increases even more the problem, rather than solving it. The only way to accomplish your desired goal of have a very responsive horse it to back down to a less severe bit, and give the horse’s mouth time to reabsorb the calluses so he/she can again feel a bit, and then teach the horse to listen for and respond to micro-miniature changes in your tension on the reins. This is, obviously, not a quick fix, but it can be done, and the result is actually worth the effort, because the end result is a happier horse and a rider who can literally ride and control the horse in his/her finger tips.