Gaining Weight, Extreme Back Pain And Migraines. Have Regular Menstrual Cycles. Am I Pregnant?

Hi! I m Amy. I m 21 years old & a little on edge recently because I think I might be pregnant. Sometimes, I feel like my stomach is bubbling or like I m hungry, but I don t pass gas or my stomach doesn t growl. I ve gotten my periods for about 2-3 days each cycle for the last 4 months & I ve also been gaining what seems like a lot of weight. I ve experienced the worst migraines that last for at least an hour & I ve also been having extreme back pain . I know the best way to know is to take a pregnancy test or see a doctor, but I really need to know, because I ve never had a baby before, whether or not these are all symptoms or perhaps something else. I haven t had morning sickness , that s what makes me skeptical. Please help me! -Amy