I have the exact opposite problem (VERY tall), which means that scrubs look like high-waters and my wrists hang out of my whitecoat. I would get the smallest one you can find (try to get the "thinnest" one) and then just hem the sleeves. I've bought a whitecoat or two and let out the seams at the wrists. Just like with regular clothes, I swear that manufacturers think that women hit 5'7" and then just get fat. Grrr...
Also, being slightly on the large side is OK, since you'll always be wearing it OVER your clothes.