I think there's 2 things to point out:
The posture in the ref is usually a bit more dynamic than what you put on paper. With the measurement exercise it's not about the gesture, but I think it might be worthwhile to keep that in mind as it can help you look for spots where your measurements are off.
The other thing is linequality and especially lineeconomy. For the measurement exercise I'd personally try to make my lines as clean as possible. With your lines there is oftentimes a lot of ambiguity, which isn't necessarily bad in terms of artistic value (and in fact your lines are still appealing to me) but it makes mistakes way harder to spot.
That being said, your measurements are quite close so I don't really see a problem, just something you can keep in the back of your mind for future attempts.