Am I Pregnant Or Is It Something Else...?

Hello, i'm kinda new on here ...My story is that i'm on the pill and have been for like 3 years now well i've always started on the same day forever no matter if it's morning or night well in nov. My period was 4 days late in dec. It was 2 days and this month is was 1 day and with the pill it makes you have your period and this period isn't what I call "normal" you would think okay I started later then I should go the whole cycle well it's not i've started late and it will only last 2 or 3 days and it's not heavy like I thought it to be and in dec. I messup up my pill like one day taken it at 9 a.M. And one day 3 p.M. Not on prepose just with christmas and everything; everything was just busy. ..My question is could I be pregnant even though i've had my periods ..This month i've have felt so fat and have been eatting a lot but then after I eat I kinda fell sick and i've been so tired and I know i've gained weight b/c my pants are tight..My annual check-up is in two weeks should I wait intill then or what...Because i've heard and read that if you keep on the pill while pregnant you have the chance on the baby having a 10-20% defect on the baby.. please help...