Desperately Needing Help

Okay I have a problem. I've been thinking about it desperately for the past 4 hours or so, only to reach no conclusion. So I've decided to ask the public for advice.

The formal is 5 months and 4 days away, and I realise that it is way too early to go looking for dresses already, but I can't look for the dress before the formal because we have too many exams, so I intend on buying /designing+making my dress in the upcoming holidays.

So I was looking around for ideas and inspiration, when I came across the most beautiful dress ever:

Only, I wouldn't have all the sparkly stuff. My version would be dark sea green with black lace on the bodice and maybe some at the bottom. Problem is, its way too long. I could make it touch the floor, but that would still be too long. And why not just simply make it knee-length you ask? Because it'd look hideous. Can you imagine that dress knee length? HIDEOUS I tell you.

But that's the problem. The dress is beautiful, but its too long. So I can either:

a) Make that the dress for my Year 12 formal, which is more important and more formal clothes are required. But I'd have to think up a new idea for this year's formal dress, and I can't wear this astonishing compliments-guaranteed dress. Or
b) Wear this dress. Look great. Figure out a dress for Year 12 later. Suffer having to wear a super long dress where most other people would be wearing a knee-lengthed dress.

So. What to do?