@Matt-And-Tanya0 Well, join the rest of us! But kidding aside, you need to know that well established listings such as yours drop down in the search rankings as new listings are put up. New listings get a temporary boost by being put at the top of the searches just so they can get started.
That said, are you searching as a guest would? Many hosts make the mistake of just looking at listings without any filters and are dismayed where their listings show or, in the case where there are 1,000's of listings, the fact their listings don't show at all.
I suggest you search using filters such as listing type, price, amenities, number of people, etc. When you narrow the search I'll bet you find your listing well positioned.
You might also be interested to read this Airbnb article:
https://www.airbnb.ie/help/article/39/how-are-search-results-determined
Hope this helps!
Hope this helps!