Based on the numbers you provided ($304,000 balance, 4.325% interest rate, $2,216 P&I payment) the loan will be paid off in July of 2032. You have 190 payments left and you will pay just over $116,000 in interest over those 190 payments. I assume you rounded your balance and payment so these numbers are not exact, but pretty close.
One thing you may think about is refinancing your loan. If you plan on staying in this home for the long term, or at least owning it for a long time even if you are not living there (rental?) then the numbers start making sense to consider refinancing it down to a 15 year loan.
For example, if it is your primary home and you have good credit you should be able to get a rate someplace around 2.625% (I just refinanced an investment property down to this rate). You would have 180 payments left, pay just over $64,000 in interest and your P&I would drop to $2,045. You would save $171 a month on your payment and $52,000 in interest over the life of the loan. You would have to pay the closing costs which should not be more than $8k (assuming you buy some points to get the interest rate down).
I just went on
www.aimloan.com and ran a quick rate quote. I assumed you have good credit, the house is still worth $440k, your loan would be $304k, and I picked a random state and county. It came back with even better numbers because it is your primary. They were quoting a rate of 2.25% with only 1.7 points and $7,800 in closing costs. You would save $62,000 over the loan in interest, save $225 off your monthly P&I payment (another $40k over the 180 payments) and shave off 10 payments (another $22,160). In total, if you refinanced and got that rate...you could end up saving yourself $124k!
My numbers may be off a little, but they are close enough to know that you are in a position that refinancing makes really good sense if you plan on owning this house long term. There are some refinance calculators out there (just google them). I would use
www.aimloan.com to get a quick quote to get a ballpark idea of what you could be looking at and then call/look at other sights to see what your options might be.
Hope this helped and good luck!