I Don't Know Which One To Believe?

Ok, So I've Been Feeling Nauseous for the past 3 days. Which I attributed to me starting a new diet and exercising but today my mom suggested I take a pregnancy test which I did. To my surprise the control line was dark pink and the test line was light pink. I just couldn't believe it. Now because I am a skeptical person I went out and bought a CVS Digital Pregnancy Test and tested once I got home. Sadly it said "Not Pregnant". What should I believe? I don't want to get my hopes up but i'm just too confused..someone please help...Thank You