I agree with the concensus here. It sounds like you would need a medium.
I'm almost always a small at Talbots. But lately, their tees have been more fitted and tighter than I like to wear, and longer. So I've switched to petite medium, for tees only. For sweaters and shirts/blouses, I buy size small.
Since things are always changing in retail, it can help to go into a store and try things on. I still do this occassionally even though I do most shopping online.
The sales people at Talbots aren't pushy, in my experience. Also, you can use the store phone to make a catalog order and get free shipping.