Don't let anyone stop you from working. This painting shows you are working with modeling, using shadow and light to make the two dimensional surface appear to have depth. You're at a disadvantage working from a photo because it's obviously flat and a reproduction of a reproduction having lost much quality of the original. It's also probably smaller than your canvas.
All that means you're filling in a lot of things that are difficult to see in the original. You would be better to spend your time working from life, people sitting in front of you, so that you learn more about how to show form and weight and dimension, and to give them a presence. That's all very hard to do working from a photo.
As far as what you've done people will be critical since we're mostly all familiar with the source photo. You've gotten his features a little off. It has hope, but it seems like a sketch that needs to be repainted into or else move to the next one and then observe your progress. There are infinite ways to interpret the original photo but, if you didn't, you should have gotten a pretty good contour drawing in pencil to get started anyway.
Keep working. It's obviously a student work so the point is to learn and get better. Good luck.