Don't be hard on yourself Sarah. It happens.
Its so common for them to get matts under their front legs. I too struggle to groom Millie. I took her to my friend to prof groom and she found matts I didn't even know she had. But hats off to her she got them out without compromising her long fur coat.
I've now found one on each side of her neck, right below the ears. They are proving so difficult to remove.
I have accidently discovered that when I go to bed and Millie joins us on the bed for while, I can groom her fairly easily
Not an ideal time to start grooming, but I'm making great headway 
Its so common for them to get matts under their front legs. I too struggle to groom Millie. I took her to my friend to prof groom and she found matts I didn't even know she had. But hats off to her she got them out without compromising her long fur coat.
I've now found one on each side of her neck, right below the ears. They are proving so difficult to remove.
I have accidently discovered that when I go to bed and Millie joins us on the bed for while, I can groom her fairly easily