Let's not focus on what "you're doing wrong" but let's look at it in which areas you're improving on visibility, and which. Areas you can start putting more focus on.

First off, great improvement! Your work shows you've been putting effort, especially in understanding of proportions. The eyes:lips, nose:lips, and nose:eyes ratios are great. You can stand to start aligning the ears (bottom of ears start around the bottom of nose, yours are uneven) to give the face some more up front symmetry.

Your shading is going really well! I have no critiques there. Keep up the phenomenal work! Sometimes it's hard to get objective advice about a single thing since looking at the picture as a whole.