First of all, I think if you can play it extremely well, and make it sound really scary, there's nothing wrong with it being a bit slower than the 'recommended speed'. It's your interpretation, and I doubt Chopin put 176 bpm on his manuscript!
However, if you just can't stand the way you're playing it, and deep down believe that the extra 21 bpm will make all the difference, I would recommend several things.
Away from the keyboard, practice hearing the entire piece, from start to finish, at the tempo you wish, with as much musical detail as you can imagine.
At the keyboard, practice each hand separately, from beginning to end, with the metronome at 176.
Play the entire piece hands together with the metronome at 155. Play it again at 156. Play it again at 157. Play it again at 158, etc... and before you know it, you'll be right there at 176!
Can I ask you how many other Chopin Etudes have you played?