The situation will not get any clearing in the years to come:
You seem petrified to make a decision; yet, when you do, you will be right and you will be wrong.
You sound like you are contemplating selling becuase you want to move UP, into a larger or better house. You didn't mention Job-Relocation, retirement, or Moving to another State.
If you are Moving Up; your present house will continue to appreciate, and so will your next house; but if the next house is better and more expensive, then it will probably be going up more and faster.
Talk to a Realtor and relax:
It is one of the three most stressful things that could happen in your life; just go for it!