I agree... if you see 2 lines you are pregnant. I also was doubtful whether or not I was pregnant. But here I am 22 weeks in and I'm expecting a baby girl(: but I'd also try to test again in 3 days. Maybe you could try clear blue or first response. When I took my first pregnancy test I was 8 dpo and though it was very very faint I had a line. I followed up with another at 13 dpo and the line was very noticeable.
I say no matter what the line is, you are pregnant. Not sure about beta since I don't know much about it. Have you taken another test to see how to line looks