ivman,
Your job is indeed a very hard one. Facing all the "difficult" things. Furthermore, you need to be on shift. It's definitely not easy for a devoted mother like you.
My husband's sister is a nurse. She is single. Thus, she could still manage. Her mom is still taking good care of her. However, I really respect her in what she does. This is why, I fully understand your situation and the difficulties that you are facing as you are taking care of EVERYONE both at work and at home. You need to make use of the break-time to sleep and not to cook. Otherwise, it's hard for you. Remember, you need to be healthy as well.
Try hard first to see if this job could make you become a professional.
If I have part-time, I'll let you know.
Anyway, keep up and see if you could manage in this new model.