(1) Your username is linked to this blog http://thehoppyfungo.wordpress.com/
And your avatar is displaying here in the forum. Is it the one in question?
(2) Did you just add your avatar? If so it may not be retroactive and therefore may not appear on earlier comments you made. There's also a time delay for displaying avatars to take into account.
(3) If you have another blog and now want instructions for linking your username to it then here you go. We all have two profiles at wordpress.com. One on our blogs and one here in the forum.
Here’s how to link your username to your blog in your blog -> Users -> Profile
In the right hand column locate “Website” and type in the link to your wordpresss.com blog example: http://myblog.wordpress.com
Linking your username to your wp.com blog in the forum
(1) Go up to the top right hand corner of this forum page and look for “Welcome,_________ ! View your profile” and click “View your profile”.
(2) Next click “edit this information”.
(3) Complete the fields being sure that where it says website that you enter http://insertyourblognamehere.wordpress.com (no period at the end or the link won’t work)
(4) Once you’re done click “Update Profile”. Voila! Now every time you sign into the forum we can click on your username and your blog will be linked to it.
(5) Also note that there is a complete record of every post that you make to the forum on your forum profile page. Everyone in the forum can access it by simply clicking on “Member” next to your username. :)