Can my boss fire me?

 I work in a Nail Salon with a tough Vietnamese boss lady. In the last month I have called off work 3 times. 1st my son was throwing up. 2nd I was having some bad morning sickness 3rd My son and I have some bad runny noses, sore throats, and coughs.    I didn't have doctor notes for the others, but today I'm going to get one since I'm taking my son to the doctor this time. She doesn't know I'm pregnant. And according to the government I am self employed but trust me I don't get treated like I am with this career.