Wth they say it only takes one time but seriously??

So im 12 weeks PP EBF he was a preemie at 33 weeks i just had something in my head saying test even though we only dtd ONCE since he was born so i did i few days ago thought i saw a hint of a line but it was ic so bought frer i still don't know if it's for sure positive but if it is will i be able to breastfeed my lo? I know i can but if any of you got pregnant right after having baby when did your supply start to drop off or deplete? With him being preemie i really want at least a year but would've loved 2 years. That's obviously only one concern as im terrified this would be#7 😱 not planned at all but one concern at a time im so scared