Hiya~
Sorry it took me some days to answer you, I'm pretty busy in real life and rarely get myself the time to answer comments and PMs. ^^; Oh and I'm replying on your profile 'cause I can't send any PM at the moment since my inbox is full. XD; Hope you don't mind. ^^
If someone asks me something they'll definitely get a reply sooner or later, and don't worry, you're not bothering me at all! =D On the contrary, I'm glad of your question. ^^
The doujinshi you see on my LibraryThing account are the ones I own or plan to buy (depending on which collection you checked ;P). I put none of my downloaded doujinshi on that account because I want to use it only for books I actually have in my possession.
This doesn't mean I don't have any downloaded doujinshi though XD (I actually have more than 1 Gb of downloaded Hetalia doujinshi on my computer XD). All my downloaded doujinshi come from the Hetalia Community on LiveJournal:
http://community.livejournal.com/hetalia/. If you're not a member or don't have a LJ account I reccommend you to join/subscribe to the site. =) All the R18 rated material is community-locked, as all the downloads (including doujinshi). Once you're part of the Community you should just use the tag 'doujin' to see the posts you're interested in. ^^
You would maybe want to have a look at this thread in one of my clubs:
http://myanimelist.net/forum/?topicid=73903. It's pretty old now and unfortunately I still didn't had the time to write any update, but you should find those links very interesting if you're looking for USUK doujinshi. ^^
Just one little question: do you understand Japanese? 'Cause most of the doujinshi you'll find on the Internet are in RAW I think. =P