Am I pregnant

I went on the depo shot a month and half ago, I waited for 7 days until I could have sex. I’ve been having spotting of blood etc whilst on it, however I did a test last week just incase, not really sure why. I got the Tesco £2.50 test and it had a strong blue line in the ‘not pregnant’ but then had the faintest line in the ‘pregnant‘ circle. You need 2 lines in both to be pregnant. So am I just over-thinking or not, am I or am I not?