Ngaire hello, Your drawing is quite good and easily adjusted. So, please do not despair for you are almost there that is perfection is the next step.
Have you heard of the Bargue drawings? Well, I hope this will help out on your next project. Whether you wish to do a comparative or sight size method this will work. There is a number of ways to start a drawing this is just one but if you wish to train your eye to see correctly than this will help. This is the method that most The art academies throughout the 19th century teach this method.
