please i need some opinions.....

Jade • Expecting mama of baby #1!!!!👶🏼🍼 due 2018
So im on birth control, and i never miss a pill, but this last month i did miss one day, now im four days late on my period and it still hasnt started. My appetite has been crazy high, and ive had some back pain. I just need some opinions on wether or not its because i could be pregnant.....ive looked some things up online but still would like some help.