Hello, I find the pose practise really promising ! For proportion : It was quite right except the legs. What I did was check the distance from the knee to hips, they match hips to shoulder on the ref, but hips to head in your drawing. So I shorten the legs I then tried to check: -> negative space (in orange) some shapes where quite distinctive but not visible in your drawing : neck, underarms. -> vertical/horizontal correspondance : foot to elbow, hips to shoulder, tip of right foot to middle of left foot. I'm far from an expert but I hope those tips helps.
Thank youuu