Please help

Ok guys so me and my bf have been together for 3 years now we never use pertection or anything. Ik for a fact it is not him though. Now me I have really bad irregular periods like months at a time wich is why I decided to get this app to help tell me when I'm fertile. Now my mom has had cervical cancer 3 times and they finally just took all her womanly stuff out. I was hoping someone could give me some pointers?