Agents may be willing to lower the commission if they both list and sell the house. When you think about what you need for the house, think about the future. Consider all possibilities and be sure you feel you can accommodate them in your new house. Remember that what you see from the outside can be deceiving. A home that looks small on the outside may be a lot larger once you get inside.
Basements especially can add a lot to the size of the house.
Purchasing a similar size new home may cost a lot more. The worst decision you can make is to buy a house and thinking you will just make do until something better is available. It takes time and money to move, and you may end up stuck in that house for longer than you think. Be sure you are happy with the house. When planning a move, keep in mind the timeframe it takes and how that will mesh with your life.