I would stop paying extra on your mortgage immediately. You would make more just putting it in a cd. With a 10 year horizon, I would actually be putting that money in the market at this point.
Also, I would strongly argue against the need for a 4000 sq foot house for 4 people, but itโs your money. Just make sure you put those numbers on paper so you see how much of your remaining life you will end up working to pay for that unnecessary space.
Unless you specifically bought the current house to be a rental, the chances of it being a great rental financially are about 0%. People who are successful in re make most of the profit up front bu purchasing unit where the numbers are in their favor. Very few single family homes meet their criteria.