overall really lovely card. Like the composition/idea a lot and the coloring is very nice.
There are a bunch of areas I think this could be improved a bit. the 2 things I want to mention are the red AA pixels around the wolf, which I think create visual noise.
The anatomy of the face could benefit greatly from some more work. As far as I read it, the characte ris looking up, while the jawline looks like it's drawn from an angle slightly looking down at the face, so it creates a rather uncanny effect.
Also I think the size distribution of the features could be changed up a little, as the mouth is smaller than an eye and the tip/ball of the nose way bigger than the mouth, leading to an effect of a quite big feeling nose.
I think by making the ees smaler, the tip of the nose way smaller and the mouth way bigger those proportions would harmonize more.
It's a lot of text and thos epoint smight be hard to bring across, and while I tried to communicate them clearly, I thought some visual aid to illustrate them would be way more helpful than more text here
https://www.dropbox.com/s/hlf0qt5rsxnx6kh/Moon_Edit.png?dl=0
Also I want to stress that I made this, because I really like the work and not because I think it's bad and needs a fix. I myself struggled with those proportions a lot as I was your age, so I thought a pointer from somebody who ha sbeen through this process might be more appreciated.
Keep up the good work and have fun with pixels 
This is such a beautiful card. I love your strong use of the blue and red, and the overall design and composition are wonderful.
Thank you so much for your comment, I was very pleased to read your review of my art :> And thanks a lot for your recommendations, they are very helpful and I think they will improve my skills
Facial proportions are hard, but I'll keep fighting >:) Thanks again, honestly I didn't expect someone to give such a detailed comment, but it's great great to get advice from a professional