jerseys too big

[VeloVT]

I'm a 34A, usually a size small jersey (about a US size 4 on top). Castelli and Gore fit me like a glove. I'm a small in Gore. I used to be a small in Castelli -- they changed their sizing in 2008 (I think?) and I haven't bought any jerseys from them since then, but I think I will be an XS in their tops now.

I would look at Craft as well.

[Bluetree]

Etxeondo (most of their line) and Assos SS Lady work for me (34A). Both have full zips and "shrink-to-fit" your torso. The Assos jersey is a bit short, tho. Giordana made a S/S jersey last year called the "Forma" that was good, too. And my team kit is by Voler and they make a full zip women's race cut that I like as well.
Castelli doesn't make full zip S/S jerseys for the most part.

[VeloVT]

That's true about Castelli, they don't do a lot of full-zip for women, I missed that the OP wanted full zip first time around.

How tall are you? At 5'6", Giordana jerseys tend to be way too short on me.

Has anybody tried Campy clothing? They have a few nice looking pieces, including full-zip jerseys for women.

[Bluetree]

I have a few Campagnolo jerseys. They look sharp but I'm not enthralled with their fabrics (not like Etxeondo!) especially for the price. The fabric is similar to the old Bergamos, before they became Capo... very thin.

[subengine]

I too run small in the boob region - barely fill an A cup! I only have a few jerseys and none are full zipper put I have a pearl izumi, jaggad and netti jersey that fit well. Jaggad (I think is an Australian brand and they have a warehouse in the U.S I think) fits particularly well. They often have cheap online sales but just check because some of the sale stock is event branded.

[subengine]

Sorry forgot to mention that in pearl izumi I fit a small but for jaggad definitely an xs. good luck!

[aicabsolut]

Race cut jerseys.

If length or fit in the shoulders is an issue for ones small enough in circumference, go with men's. I usually wear XS men's race cut jerseys.