I have a high level of trust with this realtor - I have worked with her on several transactions since 2003. And she knows me well so she knows I that I only believe concrete information :-) She is also the agent with the most sales (by far) in my complex so I know she will give me accurate and most up to date information.
Just be aware that agents are trained to get people to buy and sell today, and not to wait. This is how they earn their commissions, so their interest is completely aligned with telling you what you need to hear to sell.
We went through a similar thought process recently ourselves. Our FIRE date is currently June, 2020. We had a very unique rural property we'd bought in 2010 for 341k. It was very isolated which is a pro to some folks, and a con to others. Has a bass pond and two acres of lawn, again, great for some folks but people who want to live in a development with neighbors and BBQ's wouldn't be interested. Stairs and two levels, so older folks wouldn't be interested.
We had tried to sell in 2013 for 350k, when we moved temporarily to Hawaii for work. We had three showings in a year. Last year our daughter went to college, so we decided to try again. Dropped it to 300k on Zillow and we had an offer within 48 hours.
We tried renting but ran into a series of misadventures that convinced us we'd be happier in a house (see journal for the details). We found something a lot more marketable in a development nearby, which we're confident we'll be able to sell quickly when the time comes.
So how does this apply to you? If you're worried that it will be difficult to sell when the time comes, sell now. Then you can rent for a couple years and be confident that you'll have less details to wrap up when the time comes. If you feel it will be quick to sell, then stay where you are until you're 6 months out from FIRE. You enjoy the property and you have to live somewhere. Market risk is going to be there no matter when you sell, so don't try to time the housing market.