Wedding guest fit

This is a dress I’d like to wear to a wedding next month. I love the silhouette of it (I’ll wear a belt as well I think) but I’m not liking the neck line. Is it too big on me? Or is it meant to look like this? Also if it’s too big, is it something a tailor would be able to fix? I bought this dress last year and I swear it looked better on me then.