I measured my bust and it's almost exactly between the smallest sizes. 32" would definately be too small, and 36.25" too big. Hm. I've never knit an entire sweater before and not sure what is the best thing to do. I would not be happy to knit a million rows of stockinette to be unhappy with the fit.
Or I could try to somehow alter the pattern to make it halfway between those two sizes? But I was kinda hoping for a brainless knit for a car ride I will be on tomorrow...
If you want a close fit, you should probably go with the smaller size. If you'd like it a little looser or plan to layer, the larger size would probably be ok.
I had the same situation, where I was between sizes. I have approx. 35" bust and went up to the 36" size since it was the closest. I modified the size across the bust slightly by adding waist shaping, decreasing 12 stitches total for waist, but only increasing 8 stitches to the bust. It's a little looser than I would have liked, but this could at least partly be blamed on my yarn unexpectedly growing when it got wet (I tried checking for this with the gauge swatch, but apparently this wasn't noticeable to me at the time). I had really hoped for a sweater that could be worn without layering, but this really requires a tank/cami worn underneath because the neck is so big.
Here's a really bad FO pic to give you an idea: