When making a logical argument, you have to be careful to avoid dogmatism. You do make an attempt at a concession by acknowledging the adoption option, but you have to present your concession and counter it thoroughly if you want to present a convincing argument.
If you are writing this argument for a class, consider what your opponent might offer as his or her primary points and who your audience is. For example, the overpopulation point might be a valid one, but not if you are arguing strictly about the United States and to an American audience. The U.S. does not have an overpopulation problem; in fact, some researchers are concerned about the lack of a youthful population to make up the working force as more and more Baby Boomers reach retirement age or face health problems. Similarly, in countries which do have significant overpopulation (China), abortion has been legal for years and has done nothing to alleviate their problems. Instead, China is facing a major crisis because so many female babies have been aborted that the nation has a very poor ratio of males versus females.
Finally, your opponent will also most likely argue that each point you offer about ethics and morality and rights also applies to the life being aborted. What are his or her rights? This then brings you into another argument about when human life begins, etc.