Clear blue

So I done a clear blue digital test Monday 2nd and it says I'm pregnant 1-2 🤗🤗 however when I googled and came on glow it calculated my when I last got my period on the first day, which says I'm 5 weeks 4 days. I guess my question is, how do I calculate it? Also this one is my first went to the doctor he didn't say much just said you came early il transfer u to the hospital.😞 and that's it. Also im still smoking I don't now how to quit I think I'm waiting for something real from the Dr so I can really believe I'm pregant..  (I guess I'm still shocked,suprised  excited 😜😜😜😜😜 I hope my bambino is ok.