This looks really good!
It always bugs me when my drawings aren't parallel, so I've come up with a system. First, use rough curves and lines to get the general idea of the drawing. Everything around us can be made up out of shapes. Focus on one piece of the drawing. (Eye, ear, hand, etc.) Once you the single part drawn out, use a ruler or straightedge to make the height and width of each part, carefully transferring these to the opposite side of the drawing. Then, use that same method to transfer over any details of the part or a new part all together. It makes the process longer, but it definitely helps.