Are you getting all of your caffiene from the medicine? Are you also drinking coffee or soda? I'm guessing no because of your comment that your family is against it.
First, I would suggest you let your doctor know, and ask her to prescribe another pain reliever. In the meantime, start reducing your dose on your ferocet w/codiene. Keep in mind that codiene can be addictive, also. Get a pill splitter from the drug store, or get a package of single edge razor blades.
During your first week, cut the pills in half, and then in half again. Take about 3/4 of a pill. I say 'about' because they probably won't split evenly. If you tolerated that OK, try taking only 1/2 pill the next week. If that's not good, go back to 3/4 for a few days, then try 1/2 again. Keep this up until you can get your dose down to 1/4 pill for a couple of weeks. By then, you should be able to substitute your new pain reliever for most of your ferocet doses.
Give it a try. I'll bet you can kick it in a month.