I haven't had a period since July

So my mom had a hysterectomy. Since June I have been living with for financial reasons since she hasn't been able to work. Which does increase my stress. But I have maybe missed 12 periods my whole life. For the past 4 years u could set a clock to my periods. I understand that women sync up. I have take. 4 pregnancy tests and all BFN, But. Could my mom's hysterectomy have messed me up. Could I be pregnant? So much on my mind. Getting discouraged in every aspect of my life