This is a fine drawing. It doesn't have to be perfect to be good. In fact, perfect can be, well, troublesome sometimes.

My philosophy is, draw the lines correctly. The form will come. Line first. If the lines are right, the form will come along. Don't sweat it if you blow it. Just do better the next time. If you focus so hard on the form, it will elude you.

Perhaps if you would have approached the hands with the attitude that you were just going to make the lines precise, and each line final, each line expressive, and with the right dynamic, the right length and angle, perhaps you would have had a better time of it. And if not, big deal. Better luck next time. But you were thinking, "Hands! Form!" Like someone who was drawing their first portrait thinks,
"Face! Head!"

I agree with Lisa. It is good.

I rarely critique anyone's form anymore. It does little good. It is better to get them to focus on good lines as they go, to inspire them to draw with greater passion for each line they draw, rather than to ignore the line for the worry about the form. If every little line is drawn correctly, guess what! The drawing will be precise!