that's a pretty big age range, isn't it? 15 to 35? i mean, what does a 15 year old have in common with a 35 year old? isn't it likely that they're going to have a pretty different style seeing as how the latter could be the former's father? just my opinion, but i think you should narrow your focus down a bit and either lean one way or another age-wise.
i don't know any teenage boy that's going to wear anything to do with butterflies, so, and again this is just my opinion, i'd be looking to cater more towards the 25-35 crowd. even then what i get the sense of is a site with some nice designs, but no strong brand.
nothing against etsy, but when i see you've had 21 sales since 2009, that doesn't do anything for me. truly, it's a huge turn off.
i didn't scrutinize your site by any means, but at first blush it looks dead or dying. since i can see the number of sales, were i an etsy follower (i'm not), my conclusion is that you're not a has-been, you're a never-was since i'm figuring in that some of those were friends and family. maybe there's something in the blog, but i didn't see an 'about us,' which is something i always check out.
of course, facebook and everything will fade away, but it's nowhere near that point yet. so what if 30,000 ppl get ticked about a change to farmville and bolt, they're not your customers anyway. it's just a matter of striking while the iron is hot, and when it's no longer in vogue you move on to the next hot thing like locust. the thing is, facebook isn't where you're doing your actual commerce, it's a doorway to your site where the real manipulation begins. some people have coupon codes, or some daily special, or *something*.
were it me, i would ditch etsy. i don't think it's a great place for most lifestyle tees anyway, no? and maybe that's one problem, you're selling designs that have some cohesion in general, but they don't represent anything. what do bison, hummingbirds, optical illusion, skulls and cards have in common? beats me. i might like the design, but how do i know it's something for me and not created for some dippy hippy living off bugs he licks off windshields up in the mountains? so perhaps, and i'm just thinking with my fingers here, more brand self-awareness would help? personally, i don't get MMA out of this stuff, but that's just me. hummingbirds and the MMA? bucolic mountain scenery that's an optical illusiong and the MMA? a panda illusion and the MMA? huh?
someone mentioned a skate shop. couldn't hurt. but, again, just because it has a skull in it, it still has HUMMINGBIRDS! lol! hey, go for it, but don't be shocked if they don't sell like hotcakes. then again, surprise me, i'd love to be wrong.
i think if you set up a booth in the right venue you're likely to kill the past three years of sales in one day, maybe like some crazy mountain jamboreepalooza.
personally, reboot with a new site, a market with a narrower focus, nail your niche, and design towards their tastes while keeping your brand identity in mind. i do like your designs... i'm just not sure i'd buy them, ya know?
just a couple of thoughts, hope it gives your brain a snack.