Hi there. I like what you make. I am definitely no letterpress/paper expert (though I worked at Paper Source once upon a time) but it seems perhaps a bit heavy on the thank you cards. I know Etsy is big into weddings and personalized things involving everything having to with weddings, so maybe you could gear a little more towards wedding invitations or save the dates??? Also, I noticed your photos seemed a little washed out compared to how colorful your cards really are. I might change the sections up a bit and do a "blank cards", "wedding invites", "thank you cards" something like that, because whoever visits your shop will most likely be on a mission. Then offer single cards, packs of 10, packs of whatever within those sections??? Again, I really have no idea, but I'm just thinking aloud here. I used Picnik.com to brighten one of your photos and will send it to you in a convo so you can see what I mean about your colors seeming a bit washed out.
I don't think you are doing anything "wrong", it just seems there is a lot of competition in your field, and if your cards don't pop against the sea of others then they may become overlooked.
-Evie