Hey! I recommend focusing on drawing a base using the Loomis head method to establish better proportions. The face looks disproportionate mainly due to the lack of structure, and the Loomis head can help you a lot with that. As you mentioned, the hair is too big, making the upper part of the skull look too elongated Maybe the resemblance isn't exactly what you had in mind (since I don't know if you used a drawing as a reference for this portrait), but I tried to correct the overall proportions and structure of the portrait. Notice how drawing a Loomis head beforehand helped me achieve better structure and a better overall appearance for your character. :) Hope this helps!
Thank you for advice and I don't really know how to do references with the image but it's from a scene from the summer Hikaru died but thank you for the help and tips