Trading homes is possible. The buyer who is purchasing the larger home would pay the difference in the sales price. The problem is that finding a buyer willing to buy your home and you wanting their home can be a little tricky.
It is a better idea to sell your home and then after that transaction, you purchase a larger home. You could negotiate with the buyer to rent your home until you find a new one or you could rent somewhere for a few months. Another option is to time the sale and purchase so that you close almost simultaneously. If your income is high enough, you might even be able to close and move into your new house before the old one closes, but then you would have two mortgage payments which isn't very much fun.
Either way, congratulations and good luck!... more