Okay, good news is that I was exactly where you are now. Same concerns and everything.
My end result: The top is snug, but it is supposed to be. I can pull it over my head and body. It does indeed stretch a little bit.
If I were to knit it again here are the changes that I would personally make:
I'd maybe leave out a bust decrease. I would have like a tiny bit more wiggle room.
I'd definitely leave out a waist decrease or two.
With out a doubt I'd make mine longer as it came right at my hips. Not at all like the one pictured.
I am going to knit it again, but with a wool silk yarn.
The Tilli yarn will stand up to at least one frog. I had to unknit a few sections myself. It will get pilly with too much friction though.
Great pattern, nice yarn, but it doesn't make for an enduring knit. Hence I'm knitting it again in another yarn. It is just a lot of money for a delicate sweater. Plus my yarn had a lot of knots. Very frustrating.