Ballerina shoes will get really painful after a whole day on your feet. You need something with arch support.
Cargo pants are not professional.
The most basic thing you can do is: slacks, cardigan + tee or sweater, plain socks, black shoes.
You probably need 1 each of a pair of plain black slacks, plain black khakis, and then either brown or gray slacks, whatever goes with most of your clothes. You can wear each twice and do laundry on the weekends.
Sweaters are fine. Nothing see-through without a camisole or tee underneath. When you put on a shirt/sweater, stand up in front of a mirror and raise both your arms in the air. If you can see the skin on your abdomen, then the shirt is too short and is inappropriate. Then bend over, and if you can see your breasts/bra then the shirt is too low cut and is inappropriate. If you can see the cleavage between your breasts when you are standing up straight then the shirt is definitely too low cut and you must wear something under it.
For skirts, then should be just above the knee or longer. Sit down, and if the skirt rides up past the half-way mark on your thigh it is too short. Also try going up and down stairs in the skirt. If it is too tight, you'll be too slow and may have a hard time keeping up on rounds.
Med students wear short white coats in the US. Do NOT wear your long coat.
If you don't already have these sorts of clothes, I actually recommend Old Navy because it is cheap and durable. Their "perfect khakis" come in lots of colors and lengths (you want black, tan/khaki, and probably brown or gray). They have simple cardigans that aren't expensive and you can then just get a couple of tees to go underneath. Everything is machine washable, which is key.
