Is it normal to have stress, worries and mood swings at same time?

First off I am a college student who is adjusting to the workload. I transferred from a community college where I did some Liberal Arts courses (before that I went away to school but major didn't work out). I am now majoring in Psychology and the workload is intense. I feel extremely overwhelmed to the point where I feel like I am not enjoying life at times. Between work and school I am really busy and am becoming stressed. I am having an issue with time management as well. I need advice.

Sometimes I get nervous at work when my manager walks back and forth throughout the store and I feel uncomfortable. I feel uncomfortable because she doesn't smile much and I feel she doesn't acknowledge my presence. One day she never asked me how I was making out during my training and just looked at me as she walked by. When I came in for the morning shift she was having a meeting before the store opened and she immediately told me not to ask any questions (she wanted the meeting to go by quickly). She seemed very nice during my interview but someone at work told me she is bipolar. This makes me wonder if one day she will flip out on me. I love my new job though! The question is how do I deal with an unpredictable manager who seems to be ignoring me?? She also tends to joke around a lot but you cannot tell when she's joking because she has a serious expression on her face. Ex: I asked her if I could go on break and she said "no" with a straight face. I said ok and walked off and then she said I'm joking.

How do I relieve the stress of college life and attract the attention of my manager?