@Louise65 , since your profile looks so good, maybe you should start working on your application letter. Take a look at this topic.
Your letter has to interest the HO enough so they will want to read your profile. This is where you can talk about things that are not explicitly stated in your profile. My recommendation is to read their listing very carefully a few times, read the feedback from previous sitters and the reviews the HO has left for those sitters. You will see what is important to the HO and will often learn things not included in the listing. See if there is some point of connection between you and the HO, such as a common interest, love of their dog or cat breed, your extensive experience with horses (a big advantage!), and go with that. As others have said, apply locally, last minute, offer to meet them ahead of time if possible and apply for sits that don’t seem to be drawing interest, such as one in a hot climate in the summer, a cold climate in the winter or an out of the way location that is not that popular. I’m sure you’ll soon be telling us about your first sit!