What are you finding difficult about measuring from photos? You should be able to measure sight size or comparatively more easily from photo than from life, because A: you don't have to worry about your model moving, and B: you can measure directly on the photo so inconsistencies in your bodies position don't effect the outcome. It looks to me like you would benefit from spending more time on each Drawing. Allow yourself the opportunity to fix the mistakes. Also, stepping back and using a mirror are valuable tools for spotting the mistakes as you go. I read that bougueareau would blink rapidly to see the essence. I find this works well for judging the drawing as a whole. For me most problems in value and proportions arise from focusing on a small portion and not seeing the entirety. To summarize, I recommend that you fix your mistakes by spending more time, step back, use a mirror, and also try blinking.