Most fantastic efforts you've put into your memorized figure, fnibbit. However, when in doubt, please refresh yourself by studying and memorizing with the reference actually in front of you. The reason why you could and should do this suggestion is because, it's a lot harder to draw anything from memory if your memory is not your sharpest. But don't give up, if you learn so much from your model, then your memories will become their sharpest with most practice as you could get.
For more details, look at this vid below.
https://youtu.be/F9wnSu40VQ8
Hope this advice is extremely helpful and beneficial.