Nice series of a darn good looking dog.
I agree with the above comments. If you cannot get physically down to the dog's level; bringing the dog up to your level by putting the pooch on a chair or couch will help. I do that and then sit on a rolling office chair to help me get down even further but still be mobile...
Here's my Sasha, who could be a sister to your Poppie, posed on a chair. I covered the chair with a length of fleece fabric which gave me a background that is plain and of a color which I think compliments the dog. I probably have twenty lengths of fabric in different colors that I use for backgrounds with various rescue dog portraits. Plain backgrounds are often the ticket with most dogs but, terrier type dogs are sometimes best shown on the ground. I wish I could get a shot of Sasha chasing a rabbit
BTW: We use a thin dog show lead to keep the dog in one place on the chair when photographing. My wife holds the lead from behind the chair and I edit out the lead in Photoshop.
I am getting an A6500 which should arrive at the end of the week. I have been told that eye focus on that camera works as well with dogs as with humans. If it does, it should be exciting to use