Your page and your website do not make it clear you are a dog walker, which is the basic need you are meeting.
Get your client base in place by focussing on this most basic aspect and then show your clients the benefits of the 'additional' element you offer (the training) that way word of mouth will do the rest and if you want to grow bigger with staff you will have created the 'demand' yourself if there is indeed going to be a demand.
I did the same with my cleaning company, started off offering the most basic cleaning service, did this very well and then found out how to elevate the service to a premium level of service with full-equipped and fully trained staff, people don't always realise the additional benefits until their friends and family tell them how much different and better a service is, once that message starts to seep through it will sell itself if it is what people want and, at that point you can pretty much name your price within reason.
Pay no attention to the price others are setting, they are offering a different level of service to you and that has not a lot to do with you, the cheaper services will have THEIR clients who would never pay more and YOUR clients will find you and they will then never settle for less than you offer and happily pay for this. This advice stands after you have establishes a 'need' or a 'desire' for what it is you are selling and at the level you are selling it of course.
Firstly, get clients on board with the basic 'dog walking' with a difference but add in the difference rather than the other way around if that makes sense. In the end the difference will either take off or not, you may find the money is in a more basic 'no frills' dog walking service that you can easily train other staff do do at lower cost to yourself in terms of time and effort.
There again you may find the 'difference' becomes a 'most wanted' thing and it will fly.
I repeat my advice to sell as 'Dog Walking' first and foremost, you know there's a market for this, this should be within the title of your website and facebook page - clarify this first, make it sound like the dog walking they want but a little more professional. If I were you I would set rates just slightly higher than the average at first, people do not value what they get for cheap or free, it's a fact. Sell the value of YOUR service. Mention words like 'trusted' and 'caring' - they are trusting you with their precious pet and their house key in many instances, mention insurance when you get it, your angle seems obscure right now if you don't mind me saying. Get back to basics at first and then people can learn more and more about your services and their benefits.