Where to start....
1) Why are you targeting retirement in 13 years? With the advice of MMM and the Mad Fientist you should go from 0 to hero in ~8-10 years. Create a realistic budget and savings plan so you can reach that goal.
2) You can begin extra contributions to your retirement accounts at 55, please do so!
3) Since you are so close to social security, I would calculate that into your retirement. Most on the forums don't because they plan to be retired for many years before they are eligible for SS benefits.
4) DO NOT make extra payments to your mortgage (if you are currently doing so please stop!). Multiple threads on the forum prove paying down a mortgage before FI can be detrimental. Your mortgage rate is so low, it is nearly free money.
5) Is 60k your household income, or just yours (or is it one and the same)?