Thomas Flaherty Illustrator Portrait

I'm starting to play around with Adobe Illustrator. To get a bit more experience with the software I made an illustration of a lad I used to work with called Thomas Flaherty. I'm quite happy with the piece however there are some issues. For example I tried making my own swatch for it but it doesn't seem to have worked well making him look somewhat fat, I need to look at a way to suggest depth within vector imagery. I am however quite happy with the texture overall - specifically his hair and beard inspired by the work of Kristyna Baczinski.