I think your work looks really good, but I do agree that I there seems to be a conflict in the style you want to use. There was an earlier thread about finding your own style by @robgale which I would read through if you haven't already, and the best advice I can give is to keep exploring until you find a style you are happy with or allow it to find you. As Holley said, try do some master studies and sketch other peoples work to see what worked in their designs and see whether it would work for you.
If you find yourself forgetting your process then I would make notes as you create, I often try and make my layers in photoshop like a step by step process so I don't get lost myself. You can then compare your process with others who do a similar style to see if you can refine your process so that you can feel comfortable in creating your artwork.
I would also recommend that you mix both your picture book work and your middle grade work on your portfolio into one place as there doesn't seem to be a big reason to have them separated and it will also flesh out the work more. Oh and add your website to your svs profile so people can see the work you do when you post