I don't live in your zone but as a general rule of thumb, you want to look for plants that are 1 - 2 USDA hardiness zones colder than that designated for your area. This recommendation is mainly if you want to keep the plants out in winter. If you have a place to bring them in that is chilled, then you can go with the more marginal plants.

Sometimes it is difficult to judge what might do well if you have no direct sun and there are ways to increase the amount of light around plants. In many cases, the plants will grow but the flowering will be reduced without that sunlight. Being south-facing, I expect that it might be a little blessing that you aren't getting full blazing sun all day, which is usually the case for south-facing.

I often recommend that people buy and plant things that they like and give it a try. I often go to a nursery looking for one thing and see something else and bring that home. Then I end up researching the care for the plant. However regarding your mention of "droughts" and "severe snow", you need to make sure that the plant gets manual watering if there is no natural rain that makes it on the balcony (if it is covered and/or enclosed) and you may want to consider protection in winter for less hardy plants. Snow is actually a good insulator and I allow my hardy plants to be covered in it, and that will help reduce the incidence of continual freezes and thaws, but again, it's dependent on how much precipitation in general, reaches your balcony and ultimately your plants.

I too live in Chicago and unlike yourself I get full sun all day long. Blessing and curse. I will tell you what I didn't have good luck with because they didn't like full direct sun. Petunas, Azalea's, any kind of Rhodedindrum. I have good luck with my morning glories, Trumpet vine, hens and chicks, Verbena. I just tend to plant what I like. I guess you may have to do what I did and experiment, but don't spend to much money on your experiment. Good luck sweetie and post some pic's when you can.