Blank test, not many symptoms

I have been on birth control since the begining of april of this year. My past two periods came on the thursday of my inactive week and they only lasted around 2-3 days. I have no real symptoms of being pregnant but i've notied a weight gain in my stomach and have been fixated on the idea that i look like i am months pregnant. i'm a very paranoid person about pregnancy and have been through an abortion so i tend to let my mind run wild. I took a pregnancy test this morning and it was blank at first and i checked back a little later and it was negative but it was blank the first five minutes nothing showed up and i've been told to disregard a test if it shows up later than it is supposed to. I'm now at work and can't take another test until later tonight. Do you think my chances are high that i am pregnant?