Trying to conceive

I went off birth control in October of 2016 and ever sense my period has been so screwy. According to my 2 apps (Glow and period tracker) one says I’m supposed to start my period on Tuesday (5-22) one says I’m supposed to start Thursday (5-24). I’ve been having some early symptoms (peeing more frequently, more tired, sore nipples and mild cramping) so I decided to test early (this morning) with a First Response Rapid Result and got a negative result. Is there anyway I could still be pregnant? I’m feeling very discouraged 😔