The fact is that even after so many years, you're not used to it. You don't know what to expect the next month, especially if you experience cramps. This month it might come with diarrhea and vomiting, the next month might be depression and insanely excruciating pain.
I am honestly so fucking jealous of girls with small boobs who can go about their days in cute little tops with no bras and without back pain. I literally couldn’t leave the house without a bra on and it is just so unfair.