Pregnancy test became positive right away

Today i stopped at the store for 2 different brand of pregnancy tests just because i have been very very tired lately and 2 days ago my nipples were a little sore but i never thought anything of it i wasnt even expecting a positive. For a while i have been getting nauseous for like 5 seconds and would go right away but i thought it was because of my weightloss pills. My thing is my last period was the 29th of aug and that period was super wierd, i only spotted in a way, the bleeding was soooo so low flow that the spot of blood on my pad was about the size of a quarter at the most but i honestly thought i was having hormonal problems. The “period” lasted what my normal period would last. I dont know what to think, could it be i was pregnant when i had my “last period” ? I have normal cycles