Design a mockup for my App

We need a nice fresh design for our app. We will provide the wireframes and general guidelines (backgrounds, ideas, logos) We just need the design. We need it 1x, 2x, and 3x sizes for both android and iphone with separated PNG images for each asset. We need it in Photoshop not Sketch. We will have a total of 15 screens + or - as we see needed with our discussion