So I’ve been having periods at the end of the month now, are usually have signs indicating that my…

So I’ve been having periods at the end of the month now, are usually have signs indicating that my periods going to come the most sign would be like cramps right now I’m having really bad back pain and I’m also having very very sore tender breast so how could you tell the difference between knowing that your period is coming and indicating if you were to be pregnant by chance