Bench pressing- How to get off the smith machine?

Ok- So I have been hitting the gym nearly everyday for about 5 years- I seem to have hit a plateau that I cannot break through- Right now I want to focus on benching- Right now I bench 225 military- and 185 incline- but both are using the smith machine- The problem is that when I try to get off the smilt machine i am only benching135 and I am wobbling all over the place to the point where it is really embarring- Is there anything I can do to work on my stabilizer muscles where I don't look like a complete idiot? I know I should have never let myself get use to the smith machine ....but now I want off. Any advice?