Is there any way one can be pregnant and have by our period some what? Even spotting between periods! Been feeling weird lately and now I'm scared can I or can I not be pregnant?

I've been feeling very off lately! Been tracking my period in this app, I am on birth control! But lately I don't know I've been spotting in between periods and if I get my period it last maybe 3 days when usually it last 4-5 days! Please any comments?