Astrid, I'm pretty new here and haven't run into you frequently enough to have a handle on your style--and style goals--to sense what works for you. For example, I was reading while looking at your pics and thinking, "Maybe this top is for work?" But then I read further down and you're asking if it's boring or frumpy, so I'm getting the idea that this is a shirt you just wear for your own self, not in a work or other restrictive environment.
That said, you could still be someone who likes certain cuts of clothing, and there's weather (cold, right?) and other issues. So I hesitate to step over the line. Personally, my thought is that you're very young and pretty, and something about the blouse does seem a little frumpy to me. Not necessarily because it's buttoned up so high. I think it could be the plaid pattern. Plaids are hard to do without looking a bit outdated, rustic, or manly.
But if this is the type of cut you're really comfortable with, please don't feel bad about it. I think you may just find some pattern that looks a little more flattering to you.
(By the way, this is completely unrelated, but am I the only one to notice that you bear a really strong resemblance to a fashion blogger named Sal? I see an uncanny likeness in your eyes and smiles. I'll post a link to her.)
http://www.alreadypretty.com/about-sally