I don't entirely have time to do a full paint over right now, but I think one of the reason you're having a hard time with the lighting/background and the cohesiveness of the painting has to do with a lack of value difference. When you look at the painting in black and white, you'll see that your darkest values are very concentrated whereas the rest of the value of the piece all sits in the midtone range. To fix this, remember that as objects get farther away from the viewer, they lose saturation and they get lighter in value. To really punch this piece up, I would decrease the intensity of the glow that's coming from I think the sun? and add some deeper values/ shadows/ more saturated pops of color.

