Does polyester grow?

Should I consider myself a failure if I pay someone to get my dress altered, when I have a perfectly fine sewing machine at home?

I do know how to use the sewing machine, and have made numerous cushion covers, a few hemmings, and altered a couple of dresses and skirts (never worn them once though).

I have this wedding to go to next Saturday. Black tie. Of course I'm DYING for an opportunity like this to splash out on some spectacular Oscar type frock. But reality hits me faster than normal this time; before I can even smile to myself at such a delicious shopping thought, I am quickly reminded of some very large over drafts and unpaid visa bills. Sadly, this is probably evidence that I am becoming a somewhat responsible adult.

The nearest item I have that resembles something passable as black tie attire would be this black satin-effect 100% polyester dress I bought at Whistles (nice shop by the way) some ten years ago. It's a size 8 but for some incomprehensible reasons it has gone really roomy and I look kinda pregnant wearing it. So I need to have it taken in at the sides a bit to not give people the impression that I'm fatter than I really am. "People" as in strangers, of course. If you'll be in a room full of non-strangers, their opinions about what you are wearing would hardly matter at all.

God... and there's the shoes and purse and earrings and what not to think of as well. B is having such an easier time - he's renting a tux.

Anyhow, that's my headache at the moment. What-To-Wear. I hope I have your sympathies.