I did both, and so far, I'm okay with it. I'm okay with it for a lot of reasons.
1.) I can easily alter the dress to put a corset back in, which I wanted anyway, so the fact that it's an inch too small for me is a non-issue.
2.) I still like my dress. I opened up the canvas bag I'm keeping it in at my parents house to check what the measurements are (aka had I lost enough weight over the summer to fit into it yet? answer: no) and I sighed with delight. It's just so pretty!
3.) I could be spending my weekends frequenting the bridal salons, attending RoTB sales, and going to the BABC events. Instead, I spend my weekends running, cooking, biking, watching TV, and doing my homework.
4.) I don't have to strip down in front of a pushy saleslady who tells me that I have to find the one ever again.
5.) I know what my dress budget is, because I already spent the money. I'm not trying to shave numbers off the dress budget, saying "oh, I'll only spend $200 instead of $1000." I'm not struggling because I fell in love with a dress that is $3000 when my budget is only $1000.
6.) It's done. It's just done. I don't have to scour magazines and websites to find the perfect dress, locate a salon that carries that line, go there, try it on, be disappointed by either the fit or the price, and I don't have to make a big decision over how much to spend.
I find it comforting to know that I could do these things, if I really decide I don't like my dress. (Or I let my secret and irrational fear that pick-up skirts are out of style rule my life.) I can spend six hours at a bridal salon trying on fluffy white cupcake dresses. I can spend hours paging through bridal magazines searching for "the one". I can even spend a lot of time perusing used wedding dress websites. But I don't have to. It is very, very freeing to know you already have your dress - and you bought it because you liked it; not because you ran out of time or because your mother loved it, or because the saleslady talked you into it. It's also very freeing to not worry about still finding a dress, and I think if I had tried my dress on at Filene's and not bought it, I would probably be sad I let it slip through my fingers. And I would be ridiculously sick of looking at pictures of dresses by now.