I think you have a great start here. If you struggle with proportions, take a very small ruler and compare the width of the each eye, compared to the width of the mouth, length of nose, upper lip etc. You may be off a little right now. Although I don't know that to be the case. If those measurements are off, a few small adjustments should work for you.
The only suggestion I could give you would be to look for slightly darker shadows on the faces. I never take selfies, it scares me!
So I'm not sure how well the shadows show up. I hope this helps.