It looks good
With the proportions, does it really matter?
I recon this looks cool with the over sized fins. You don't always have to change the look of a model for the sake of having perfect realistic proportions. Sometimes it seems that people forget that 3D art doesn't have to be 100% realistic all the time and it can have a different look and style to it. If you want realism just take a photo. It depends what you are aiming for, and this is just my opinion. dismiss it if you want.
keep up the good work though

also, his neck kinda looks like a foreskin...