New to birth control?

OK i started birth control 11th of last mth and the next day i started my period and it last almost 8days normal i last 3 to 4 days and last 2weeks my gotten bigger and been killing me and my and i scheduled to start today nothing at all no signs nothing no back ache and i always get that just my and been killing me and these damn headache that i have had the last week and half and i had feb. 4 but that was the last time what do yall thank i missed i birth control pill last week but i have not had since feb.4 but first time on b.c and iam 23 any help is good thanks