Try roughly blocking in the forms before you worry about pixelling individual features. It's easier to get the mistakes out of the way if you're not spending time pixel-polishing every single one.
Don't put the details in until your forms look like a cat without the details. In reality, you can tell a cat is a cat if you squint or put on someone else's glasses, that's because when the details are blurred, you still see the forms, and that's the important thing. You may even want to do this when you look at reference images - squint so that the image is blurred (or blur it heavily in Photoshop), and pay attention to the general shapes that emerge and how they correspond to the 3D form.
I recommend doing some studies from ref to get a feel for the form of a cat's head. The outline you drew looks good, but the shading within doesn't correspond to anything. A cat's head is basically a sphere with the muzzle sticking out of it, and the areas around the eyes are gentle dips/flats. Think of the shadows that would create. Don't think of your work as a flat thing, imagine the 3D forms you're depicting. If you don't know what those 3D forms should be, look at cats. If you don't have a cat you can look at, there are plenty of photos and videos online, the Internet loves cats. You don't have to draw them all, just pay attention to what you see, break it down into basic 3D forms and try to understand how they're put together.
You may also want to take a step back and do some exercises drawing simple 3D forms like cubes, spheres, and cones. It's is a common exercise for artists, but it looks like you skipped that step. By learning to draw basic 3D shapes and to think in those 3D shapes, you'll have an easier time drawing more complex 3D objects of all sorts.
