With manslaughter, the sentences vary wildly and the judge has a lot of discretion in terms of the sentencing. Voluntary manslaughter is a felony offense with a minimum 1-year sentence, maximum twenty years, so that could cause him to serve a longer sentence than involuntary manslaughter, which has a sentence range of 1-10 years if the act which caused death was an unlawful act, but can be punished as a misdemeanor if it is found that the act which caused death was a lawful act.
As far as getting a new lawyer, it sounds as if your boyfriend has not been sentenced yet, so I would recommend that, once sentenced, his attorney should file a motion for new trial and prepare to withdraw from the case and, hopefully simultaneously, a new attorney can come in to handle the motion for new trial and, if necessary, the appeal. Some will tell you to get the new lawyer in ASAP and that certainly is not a bad idea, but you are probably not hurting him by letting the lawyer who handled the trial see it though to sentencing b/c it would be hard for the new lawyer to familiarize himself or herself with the case to a higher degree than the trial lawyer in the time before sentencing.
Make sure you hire an attorney who specializes in criminal appeals.
James L. Yeargan, Jr. is licensed to practice law in the State of Georgia. All information given is based only on Georgia law, and is not directly applicable to any other jurisdictions, states, or districts. Any answer given assumes the person who asked the question holds a Georgia Drivers License, and this license is not a commercial drivers license (CDL). This response, or any response, is not legal advice. This response, or any response, does not create an attorney/client relationship. The response is in the form of legal education and is intended to provide general information. Any state specific concerns should be directed to an attorney who is licensed to practice law in that respective state.