Fox on silk

I am trying myself on silk painting. I loved doing this when I was going to school and in my late teenage years.
Have learned to do it in a therapy when I lived at the Children's house.
But I haven´t done it for many years now but still have the materials so yeah wanted to get back to it a bit.
I think this is quite good, but I have a problem and don´t know what to do. I think of buying some new line paint.
I actually have two line paints, one which I use usually. It comes in a glass and you use a brush to get it into the silk. The lines look fluent and good, but the problem is, the paint is not so heavy and the colors go over the lines which you see here and which I try to prevent all the time. Sadly it does not work, and I am a good painter, I don´t go over the lines with my brush.
Then I have another one in a tube, but I have to push the tube so heavily that my hands shake and shiver and I just don´t get fluent lines which annoys me, yet the paint is of better quality and the colors don´t go over the lines.
I have no idea what to do.