Pregnancy Spotting

I was wondering how much weight others gained during their pregnancy?
Did you get stretch marks, and what month did you get them?

For the last few days I’ve been lightly spotting, it started a few days after I was supposed to get my period. But I’ve been also having signs that I may be pregnant, sickness, cravings, and such. I wanted to know if I take a pregnancy test, will it give me a wrong reading if I test before the spotting stops?